diff --git a/README.md b/README.md
index a852b2a2..50dcc3ae 100755
--- a/README.md
+++ b/README.md
@@ -126,16 +126,16 @@
| | Easy | Medium | Hard | Total |
|:--------:|:--------:|:--------:|:--------:|:--------:|
-|Optimizing|33|33|24|90|
+|Optimizing|33|32|24|89|
|Accepted|**285**|**388**|**115**|**788**|
|Total|499|1003|399|1901|
-|Perfection Rate|88.4%|91.5%|79.1%|88.6%|
+|Perfection Rate|88.4%|91.8%|79.1%|88.7%|
|Completion Rate|57.1%|38.7%|28.8%|41.5%|
|------------|----------------------------|----------------------------|----------------------------|----------------------------|
## 二. 目录
-以下已经收录了 698 道题的题解，还有 11 道题在尝试优化到 beats 100%
+以下已经收录了 699 道题的题解，还有 11 道题在尝试优化到 beats 100%
| No. | Title | Solution | Acceptance | Difficulty | Frequency |
|:--------:|:--------------------------------------------------------------|:--------:|:--------:|:--------:|:--------:|
@@ -242,7 +242,7 @@
|0101|Symmetric Tree|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0101.Symmetric-Tree)|49.0%|Easy||
|0102|Binary Tree Level Order Traversal|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0102.Binary-Tree-Level-Order-Traversal)|57.9%|Medium||
|0103|Binary Tree Zigzag Level Order Traversal|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0103.Binary-Tree-Zigzag-Level-Order-Traversal)|51.0%|Medium||
-|0104|Maximum Depth of Binary Tree|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0104.Maximum-Depth-of-Binary-Tree)|68.9%|Easy||
+|0104|Maximum Depth of Binary Tree|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0104.Maximum-Depth-of-Binary-Tree)|69.0%|Easy||
|0105|Construct Binary Tree from Preorder and Inorder Traversal|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0105.Construct-Binary-Tree-from-Preorder-and-Inorder-Traversal)|53.8%|Medium||
|0106|Construct Binary Tree from Inorder and Postorder Traversal|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0106.Construct-Binary-Tree-from-Inorder-and-Postorder-Traversal)|51.0%|Medium||
|0107|Binary Tree Level Order Traversal II|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0107.Binary-Tree-Level-Order-Traversal-II)|56.1%|Medium||
@@ -376,7 +376,7 @@
|0235|Lowest Common Ancestor of a Binary Search Tree|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0235.Lowest-Common-Ancestor-of-a-Binary-Search-Tree)|52.8%|Easy||
|0236|Lowest Common Ancestor of a Binary Tree|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0236.Lowest-Common-Ancestor-of-a-Binary-Tree)|50.4%|Medium||
|0237|Delete Node in a Linked List|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0237.Delete-Node-in-a-Linked-List)|68.4%|Easy||
-|0238|Product of Array Except Self||61.6%|Medium||
+|0238|Product of Array Except Self||61.7%|Medium||
|0239|Sliding Window Maximum|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0239.Sliding-Window-Maximum)|45.1%|Hard||
|0240|Search a 2D Matrix II|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0240.Search-a-2D-Matrix-II)|45.9%|Medium||
|0241|Different Ways to Add Parentheses||58.1%|Medium||
@@ -714,7 +714,7 @@
|0573|Squirrel Simulation||54.3%|Medium||
|0574|Winning Candidate||53.7%|Medium||
|0575|Distribute Candies|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0575.Distribute-Candies)|64.6%|Easy||
-|0576|Out of Boundary Paths||36.4%|Medium||
+|0576|Out of Boundary Paths||36.5%|Medium||
|0577|Employee Bonus||72.6%|Easy||
|0578|Get Highest Answer Rate Question||42.5%|Medium||
|0579|Find Cumulative Salary of an Employee||38.7%|Hard||
@@ -767,7 +767,7 @@
|0626|Exchange Seats||67.0%|Medium||
|0627|Swap Salary||78.7%|Easy||
|0628|Maximum Product of Three Numbers|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0628.Maximum-Product-of-Three-Numbers)|46.7%|Easy||
-|0629|K Inverse Pairs Array||33.2%|Hard||
+|0629|K Inverse Pairs Array||33.5%|Hard||
|0630|Course Schedule III|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0630.Course-Schedule-III)|34.9%|Hard||
|0631|Design Excel Sum Formula||33.1%|Hard||
|0632|Smallest Range Covering Elements from K Lists|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0632.Smallest-Range-Covering-Elements-from-K-Lists)|55.2%|Hard||
@@ -805,7 +805,7 @@
|0664|Strange Printer||42.3%|Hard||
|0665|Non-decreasing Array|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0665.Non-decreasing-Array)|20.9%|Medium||
|0666|Path Sum IV||57.4%|Medium||
-|0667|Beautiful Arrangement II|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0667.Beautiful-Arrangement-II)|59.0%|Medium||
+|0667|Beautiful Arrangement II|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0667.Beautiful-Arrangement-II)|58.9%|Medium||
|0668|Kth Smallest Number in Multiplication Table|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0668.Kth-Smallest-Number-in-Multiplication-Table)|48.3%|Hard||
|0669|Trim a Binary Search Tree|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0669.Trim-a-Binary-Search-Tree)|64.4%|Medium||
|0670|Maximum Swap||45.5%|Medium||
@@ -857,7 +857,7 @@
|0716|Max Stack||43.6%|Easy||
|0717|1-bit and 2-bit Characters|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0717.1-bit-and-2-bit-Characters)|46.3%|Easy||
|0718|Maximum Length of Repeated Subarray|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0718.Maximum-Length-of-Repeated-Subarray)|50.9%|Medium||
-|0719|Find K-th Smallest Pair Distance|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0719.Find-K-th-Smallest-Pair-Distance)|32.9%|Hard||
+|0719|Find K-th Smallest Pair Distance|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0719.Find-K-th-Smallest-Pair-Distance)|32.8%|Hard||
|0720|Longest Word in Dictionary|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0720.Longest-Word-in-Dictionary)|49.7%|Easy||
|0721|Accounts Merge|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0721.Accounts-Merge)|53.0%|Medium||
|0722|Remove Comments||36.7%|Medium||
@@ -1202,7 +1202,7 @@
|1061|Lexicographically Smallest Equivalent String||66.9%|Medium||
|1062|Longest Repeating Substring||58.6%|Medium||
|1063|Number of Valid Subarrays||72.2%|Hard||
-|1064|Fixed Point||64.3%|Easy||
+|1064|Fixed Point||64.2%|Easy||
|1065|Index Pairs of a String||61.1%|Easy||
|1066|Campus Bikes II||54.3%|Medium||
|1067|Digit Count in Range||41.9%|Hard||
@@ -1211,7 +1211,7 @@
|1070|Product Sales Analysis III||50.1%|Medium||
|1071|Greatest Common Divisor of Strings||51.8%|Easy||
|1072|Flip Columns For Maximum Number of Equal Rows||62.0%|Medium||
-|1073|Adding Two Negabinary Numbers|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1073.Adding-Two-Negabinary-Numbers)|34.7%|Medium||
+|1073|Adding Two Negabinary Numbers|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1073.Adding-Two-Negabinary-Numbers)|34.8%|Medium||
|1074|Number of Submatrices That Sum to Target|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1074.Number-of-Submatrices-That-Sum-to-Target)|65.2%|Hard||
|1075|Project Employees I||66.5%|Easy||
|1076|Project Employees II||52.5%|Easy||
@@ -1329,7 +1329,7 @@
|1188|Design Bounded Blocking Queue||73.2%|Medium||
|1189|Maximum Number of Balloons|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1189.Maximum-Number-of-Balloons)|62.1%|Easy||
|1190|Reverse Substrings Between Each Pair of Parentheses|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1190.Reverse-Substrings-Between-Each-Pair-of-Parentheses)|64.6%|Medium||
-|1191|K-Concatenation Maximum Sum||24.8%|Medium||
+|1191|K-Concatenation Maximum Sum||24.7%|Medium||
|1192|Critical Connections in a Network||51.6%|Hard||
|1193|Monthly Transactions I||68.8%|Medium||
|1194|Tournament Winners||52.6%|Hard||
@@ -1437,7 +1437,7 @@
|1297|Maximum Number of Occurrences of a Substring||51.3%|Medium||
|1298|Maximum Candies You Can Get from Boxes||60.1%|Hard||
|1299|Replace Elements with Greatest Element on Right Side||74.5%|Easy||
-|1300|Sum of Mutated Array Closest to Target||42.7%|Medium||
+|1300|Sum of Mutated Array Closest to Target||42.6%|Medium||
|1301|Number of Paths with Max Score||38.2%|Hard||
|1302|Deepest Leaves Sum||85.4%|Medium||
|1303|Find the Team Size||90.0%|Easy||
@@ -1634,7 +1634,7 @@
|1494|Parallel Courses II||30.8%|Hard||
|1495|Friendly Movies Streamed Last Month||51.1%|Easy||
|1496|Path Crossing||55.1%|Easy||
-|1497|Check If Array Pairs Are Divisible by k||40.4%|Medium||
+|1497|Check If Array Pairs Are Divisible by k||40.3%|Medium||
|1498|Number of Subsequences That Satisfy the Given Sum Condition||39.2%|Medium||
|1499|Max Value of Equation||45.5%|Hard||
|1500|Design a File Sharing System||46.5%|Medium||
@@ -1719,7 +1719,7 @@
|1579|Remove Max Number of Edges to Keep Graph Fully Traversable||46.8%|Hard||
|1580|Put Boxes Into the Warehouse II||63.6%|Medium||
|1581|Customer Who Visited but Did Not Make Any Transactions||89.4%|Easy||
-|1582|Special Positions in a Binary Matrix||64.1%|Easy||
+|1582|Special Positions in a Binary Matrix||64.2%|Easy||
|1583|Count Unhappy Friends||55.3%|Medium||
|1584|Min Cost to Connect All Points||55.1%|Medium||
|1585|Check If String Is Transformable With Substring Sort Operations||48.5%|Hard||
@@ -1730,7 +1730,7 @@
|1590|Make Sum Divisible by P||27.2%|Medium||
|1591|Strange Printer II||55.7%|Hard||
|1592|Rearrange Spaces Between Words||43.6%|Easy||
-|1593|Split a String Into the Max Number of Unique Substrings||50.5%|Medium||
+|1593|Split a String Into the Max Number of Unique Substrings||50.6%|Medium||
|1594|Maximum Non Negative Product in a Matrix||32.6%|Medium||
|1595|Minimum Cost to Connect Two Groups of Points||43.9%|Hard||
|1596|The Most Frequently Ordered Products for Each Customer||85.1%|Medium||
@@ -1814,7 +1814,7 @@
|1674|Minimum Moves to Make Array Complementary||36.3%|Medium||
|1675|Minimize Deviation in Array||48.1%|Hard||
|1676|Lowest Common Ancestor of a Binary Tree IV||79.1%|Medium||
-|1677|Product's Worth Over Invoices||52.9%|Easy||
+|1677|Product's Worth Over Invoices||52.8%|Easy||
|1678|Goal Parser Interpretation||84.9%|Easy||
|1679|Max Number of K-Sum Pairs||53.6%|Medium||
|1680|Concatenation of Consecutive Binary Numbers||52.2%|Medium||
@@ -1857,7 +1857,7 @@
|1717|Maximum Score From Removing Substrings||41.7%|Medium||
|1718|Construct the Lexicographically Largest Valid Sequence||48.5%|Medium||
|1719|Number Of Ways To Reconstruct A Tree||39.7%|Hard||
-|1720|Decode XORed Array||85.5%|Easy||
+|1720|Decode XORed Array||85.4%|Easy||
|1721|Swapping Nodes in a Linked List||66.5%|Medium||
|1722|Minimize Hamming Distance After Swap Operations||46.0%|Medium||
|1723|Find Minimum Time to Finish All Jobs||40.7%|Hard||
@@ -1882,7 +1882,7 @@
|1742|Maximum Number of Balls in a Box||73.2%|Easy||
|1743|Restore the Array From Adjacent Pairs||64.7%|Medium||
|1744|Can You Eat Your Favorite Candy on Your Favorite Day?||31.3%|Medium||
-|1745|Palindrome Partitioning IV||49.6%|Hard||
+|1745|Palindrome Partitioning IV||49.7%|Hard||
|1746|Maximum Subarray Sum After One Operation||62.0%|Medium||
|1747|Leetflex Banned Accounts||68.7%|Medium||
|1748|Sum of Unique Elements||74.7%|Easy||
@@ -1897,7 +1897,7 @@
|1757|Recyclable and Low Fat Products||95.3%|Easy||
|1758|Minimum Changes To Make Alternating Binary String||58.2%|Easy||
|1759|Count Number of Homogenous Substrings||43.7%|Medium||
-|1760|Minimum Limit of Balls in a Bag||53.7%|Medium||
+|1760|Minimum Limit of Balls in a Bag||53.8%|Medium||
|1761|Minimum Degree of a Connected Trio in a Graph||38.5%|Hard||
|1762|Buildings With an Ocean View||81.5%|Medium||
|1763|Longest Nice Substring||61.1%|Easy||
@@ -1942,7 +1942,7 @@
|1802|Maximum Value at a Given Index in a Bounded Array||28.3%|Medium||
|1803|Count Pairs With XOR in a Range||44.1%|Hard||
|1804|Implement Trie II (Prefix Tree)||58.6%|Medium||
-|1805|Number of Different Integers in a String||34.7%|Easy||
+|1805|Number of Different Integers in a String||34.8%|Easy||
|1806|Minimum Number of Operations to Reinitialize a Permutation||70.6%|Medium||
|1807|Evaluate the Bracket Pairs of a String||66.3%|Medium||
|1808|Maximize Number of Nice Divisors||28.3%|Hard||
@@ -1964,7 +1964,7 @@
|1824|Minimum Sideway Jumps||47.6%|Medium||
|1825|Finding MK Average||28.3%|Hard||
|1826|Faulty Sensor||55.0%|Easy||
-|1827|Minimum Operations to Make the Array Increasing||77.8%|Easy||
+|1827|Minimum Operations to Make the Array Increasing||77.7%|Easy||
|1828|Queries on Number of Points Inside a Circle||86.6%|Medium||
|1829|Maximum XOR for Each Query||73.7%|Medium||
|1830|Minimum Number of Operations to Make String Sorted||46.6%|Hard||
@@ -1989,7 +1989,7 @@
|1849|Splitting a String Into Descending Consecutive Values||27.5%|Medium||
|1850|Minimum Adjacent Swaps to Reach the Kth Smallest Number||64.0%|Medium||
|1851|Minimum Interval to Include Each Query||42.3%|Hard||
-|1852|Distinct Numbers in Each Subarray||76.0%|Medium||
+|1852|Distinct Numbers in Each Subarray||76.1%|Medium||
|1853|Convert Date Format||89.1%|Easy||
|1854|Maximum Population Year||57.1%|Easy||
|1855|Maximum Distance Between a Pair of Values||46.0%|Medium||
@@ -2005,7 +2005,7 @@
|1865|Finding Pairs With a Certain Sum||45.8%|Medium||
|1866|Number of Ways to Rearrange Sticks With K Sticks Visible||54.0%|Hard||
|1867|Orders With Maximum Quantity Above Average||78.5%|Medium||
-|1868|Product of Two Run-Length Encoded Arrays||60.0%|Medium||
+|1868|Product of Two Run-Length Encoded Arrays||60.1%|Medium||
|1869|Longer Contiguous Segments of Ones than Zeros||59.5%|Easy||
|1870|Minimum Speed to Arrive on Time||32.4%|Medium||
|1871|Jump Game VII||24.3%|Medium||
@@ -2021,14 +2021,14 @@
|1881|Maximum Value after Insertion||33.6%|Medium||
|1882|Process Tasks Using Servers||30.5%|Medium||
|1883|Minimum Skips to Arrive at Meeting On Time||38.0%|Hard||
-|1884|Egg Drop With 2 Eggs and N Floors||70.2%|Medium||
+|1884|Egg Drop With 2 Eggs and N Floors||70.1%|Medium||
|1885|Count Pairs in Two Arrays||55.2%|Medium||
|1886|Determine Whether Matrix Can Be Obtained By Rotation||53.6%|Easy||
|1887|Reduction Operations to Make the Array Elements Equal||59.6%|Medium||
|1888|Minimum Number of Flips to Make the Binary String Alternating||33.7%|Medium||
|1889|Minimum Space Wasted From Packaging||29.2%|Hard||
|1890|The Latest Login in 2020||87.1%|Easy||
-|1891|Cutting Ribbons||54.1%|Medium||
+|1891|Cutting Ribbons||54.0%|Medium||
|1892|Page Recommendations II||40.5%|Hard||
|1893|Check if All the Integers in a Range Are Covered||48.8%|Easy||
|1894|Find the Student that Will Replace the Chalk||38.2%|Medium||
@@ -2037,9 +2037,9 @@
|1897|Redistribute Characters to Make All Strings Equal||58.3%|Easy||
|1898|Maximum Number of Removable Characters||32.0%|Medium||
|1899|Merge Triplets to Form Target Triplet||58.5%|Medium||
-|1900|The Earliest and Latest Rounds Where Players Compete||48.6%|Hard||
+|1900|The Earliest and Latest Rounds Where Players Compete||48.5%|Hard||
|1901|Find a Peak Element II||66.3%|Medium||
-|1902|Depth of BST Given Insertion Order||48.9%|Medium||
+|1902|Depth of BST Given Insertion Order||49.1%|Medium||
|------------|-------------------------------------------------------|-------| ----------------| ---------------|-------------|
------------------------------------------------------------------
diff --git a/leetcode/1239.Maximum-Length-of-a-Concatenated-String-with-Unique-Characters/1239. Maximum Length of a Concatenated String with Unique Characters.go b/leetcode/1239.Maximum-Length-of-a-Concatenated-String-with-Unique-Characters/1239. Maximum Length of a Concatenated String with Unique Characters.go
new file mode 100644
index 00000000..f75727ca
--- /dev/null
+++ b/leetcode/1239.Maximum-Length-of-a-Concatenated-String-with-Unique-Characters/1239. Maximum Length of a Concatenated String with Unique Characters.go
@@ -0,0 +1,38 @@
+package leetcode
+
+import (
+ "math/bits"
+)
+
+func maxLength(arr []string) int {
+ c, res := []uint32{}, 0
+ for _, s := range arr {
+ var mask uint32
+ for _, c := range s {
+ mask = mask | 1<<(c-'a')
+ }
+ if len(s) != bits.OnesCount32(mask) { // 如果字符串本身带有重复的字符，需要排除
+ continue
+ }
+ c = append(c, mask)
+ }
+ dfs(c, 0, 0, &res)
+ return res
+}
+
+func dfs(c []uint32, index int, mask uint32, res *int) {
+ *res = max(*res, bits.OnesCount32(mask))
+ for i := index; i < len(c); i++ {
+ if mask&c[i] == 0 {
+ dfs(c, i+1, mask|c[i], res)
+ }
+ }
+ return
+}
+
+func max(a, b int) int {
+ if a > b {
+ return a
+ }
+ return b
+}
diff --git a/leetcode/1239.Maximum-Length-of-a-Concatenated-String-with-Unique-Characters/1239. Maximum Length of a Concatenated String with Unique Characters_test.go b/leetcode/1239.Maximum-Length-of-a-Concatenated-String-with-Unique-Characters/1239. Maximum Length of a Concatenated String with Unique Characters_test.go
new file mode 100644
index 00000000..8a0c0034
--- /dev/null
+++ b/leetcode/1239.Maximum-Length-of-a-Concatenated-String-with-Unique-Characters/1239. Maximum Length of a Concatenated String with Unique Characters_test.go
@@ -0,0 +1,52 @@
+package leetcode
+
+import (
+ "fmt"
+ "testing"
+)
+
+type question1239 struct {
+ para1239
+ ans1239
+}
+
+// para 是参数
+// one 代表第一个参数
+type para1239 struct {
+ arr []string
+}
+
+// ans 是答案
+// one 代表第一个答案
+type ans1239 struct {
+ one int
+}
+
+func Test_Problem1239(t *testing.T) {
+
+ qs := []question1239{
+
+ {
+ para1239{[]string{"un", "iq", "ue"}},
+ ans1239{4},
+ },
+
+ {
+ para1239{[]string{"cha", "r", "act", "ers"}},
+ ans1239{6},
+ },
+
+ {
+ para1239{[]string{"abcdefghijklmnopqrstuvwxyz"}},
+ ans1239{26},
+ },
+ }
+
+ fmt.Printf("------------------------Leetcode Problem 1239------------------------\n")
+
+ for _, q := range qs {
+ _, p := q.ans1239, q.para1239
+ fmt.Printf("【input】:%v 【output】:%v\n", p, maxLength(p.arr))
+ }
+ fmt.Printf("\n\n\n")
+}
diff --git a/leetcode/1239.Maximum-Length-of-a-Concatenated-String-with-Unique-Characters/README.md b/leetcode/1239.Maximum-Length-of-a-Concatenated-String-with-Unique-Characters/README.md
new file mode 100644
index 00000000..58cdb2e9
--- /dev/null
+++ b/leetcode/1239.Maximum-Length-of-a-Concatenated-String-with-Unique-Characters/README.md
@@ -0,0 +1,88 @@
+# [1239. Maximum Length of a Concatenated String with Unique Characters](https://leetcode.com/problems/maximum-length-of-a-concatenated-string-with-unique-characters/)
+
+## 题目
+
+Given an array of strings `arr`. String `s` is a concatenation of a sub-sequence of `arr` which have **unique characters**.
+
+Return *the maximum possible length* of `s`.
+
+**Example 1:**
+
+```
+Input: arr = ["un","iq","ue"]
+Output: 4
+Explanation: All possible concatenations are "","un","iq","ue","uniq" and "ique".
+Maximum length is 4.
+```
+
+**Example 2:**
+
+```
+Input: arr = ["cha","r","act","ers"]
+Output: 6
+Explanation: Possible solutions are "chaers" and "acters".
+```
+
+**Example 3:**
+
+```
+Input: arr = ["abcdefghijklmnopqrstuvwxyz"]
+Output: 26
+```
+
+**Constraints:**
+
+- `1 <= arr.length <= 16`
+- `1 <= arr[i].length <= 26`
+- `arr[i]` contains only lower case English letters.
+
+## 题目大意
+
+给定一个字符串数组 arr，字符串 s 是将 arr 某一子序列字符串连接所得的字符串，如果 s 中的每一个字符都只出现过一次，那么它就是一个可行解。请返回所有可行解 s 中最长长度。
+
+## 解题思路
+
+- 每个字符串数组可以想象为 26 位的 0101 二进制串。出现的字符对应的位上标记为 1，没有出现的字符对应的位上标记为 0 。如果一个字符串中包含重复的字符，那么它所有 1 的个数一定不等于字符串的长度。如果 2 个字符串每个字母都只出现了一次，那么它们俩对应的二进制串 mask 相互与运算的结果一定为 0 ，即 0，1 互补了。利用这个特点，深搜所有解，保存出最长可行解的长度即可。
+
+## 代码
+
+```go
+package leetcode
+
+import (
+ "math/bits"
+)
+
+func maxLength(arr []string) int {
+ c, res := []uint32{}, 0
+ for _, s := range arr {
+ var mask uint32
+ for _, c := range s {
+ mask = mask | 1<<(c-'a')
+ }
+ if len(s) != bits.OnesCount32(mask) { // 如果字符串本身带有重复的字符，需要排除
+ continue
+ }
+ c = append(c, mask)
+ }
+ dfs(c, 0, 0, &res)
+ return res
+}
+
+func dfs(c []uint32, index int, mask uint32, res *int) {
+ *res = max(*res, bits.OnesCount32(mask))
+ for i := index; i < len(c); i++ {
+ if mask&c[i] == 0 {
+ dfs(c, i+1, mask|c[i], res)
+ }
+ }
+ return
+}
+
+func max(a, b int) int {
+ if a > b {
+ return a
+ }
+ return b
+}
+```
\ No newline at end of file
diff --git a/website/content/ChapterFour/1200~1299/1235.Maximum-Profit-in-Job-Scheduling.md b/website/content/ChapterFour/1200~1299/1235.Maximum-Profit-in-Job-Scheduling.md
index 29a1644b..ca4826f4 100755
--- a/website/content/ChapterFour/1200~1299/1235.Maximum-Profit-in-Job-Scheduling.md
+++ b/website/content/ChapterFour/1200~1299/1235.Maximum-Profit-in-Job-Scheduling.md
@@ -121,5 +121,5 @@ func (s sortJobs) Swap(i, j int) {
----------------------------------------------
diff --git a/website/content/ChapterFour/1200~1299/1239.Maximum-Length-of-a-Concatenated-String-with-Unique-Characters.md b/website/content/ChapterFour/1200~1299/1239.Maximum-Length-of-a-Concatenated-String-with-Unique-Characters.md
new file mode 100644
index 00000000..86d530b4
--- /dev/null
+++ b/website/content/ChapterFour/1200~1299/1239.Maximum-Length-of-a-Concatenated-String-with-Unique-Characters.md
@@ -0,0 +1,95 @@
+# [1239. Maximum Length of a Concatenated String with Unique Characters](https://leetcode.com/problems/maximum-length-of-a-concatenated-string-with-unique-characters/)
+
+## 题目
+
+Given an array of strings `arr`. String `s` is a concatenation of a sub-sequence of `arr` which have **unique characters**.
+
+Return *the maximum possible length* of `s`.
+
+**Example 1:**
+
+```
+Input: arr = ["un","iq","ue"]
+Output: 4
+Explanation: All possible concatenations are "","un","iq","ue","uniq" and "ique".
+Maximum length is 4.
+```
+
+**Example 2:**
+
+```
+Input: arr = ["cha","r","act","ers"]
+Output: 6
+Explanation: Possible solutions are "chaers" and "acters".
+```
+
+**Example 3:**
+
+```
+Input: arr = ["abcdefghijklmnopqrstuvwxyz"]
+Output: 26
+```
+
+**Constraints:**
+
+- `1 <= arr.length <= 16`
+- `1 <= arr[i].length <= 26`
+- `arr[i]` contains only lower case English letters.
+
+## 题目大意
+
+给定一个字符串数组 arr，字符串 s 是将 arr 某一子序列字符串连接所得的字符串，如果 s 中的每一个字符都只出现过一次，那么它就是一个可行解。请返回所有可行解 s 中最长长度。
+
+## 解题思路
+
+- 每个字符串数组可以想象为 26 位的 0101 二进制串。出现的字符对应的位上标记为 1，没有出现的字符对应的位上标记为 0 。如果一个字符串中包含重复的字符，那么它所有 1 的个数一定不等于字符串的长度。如果 2 个字符串每个字母都只出现了一次，那么它们俩对应的二进制串 mask 相互与运算的结果一定为 0 ，即 0，1 互补了。利用这个特点，深搜所有解，保存出最长可行解的长度即可。
+
+## 代码
+
+```go
+package leetcode
+
+import (
+ "math/bits"
+)
+
+func maxLength(arr []string) int {
+ c, res := []uint32{}, 0
+ for _, s := range arr {
+ var mask uint32
+ for _, c := range s {
+ mask = mask | 1<<(c-'a')
+ }
+ if len(s) != bits.OnesCount32(mask) { // 如果字符串本身带有重复的字符，需要排除
+ continue
+ }
+ c = append(c, mask)
+ }
+ dfs(c, 0, 0, &res)
+ return res
+}
+
+func dfs(c []uint32, index int, mask uint32, res *int) {
+ *res = max(*res, bits.OnesCount32(mask))
+ for i := index; i < len(c); i++ {
+ if mask&c[i] == 0 {
+ dfs(c, i+1, mask|c[i], res)
+ }
+ }
+ return
+}
+
+func max(a, b int) int {
+ if a > b {
+ return a
+ }
+ return b
+}
+```
+
+
+----------------------------------------------
+
diff --git a/website/content/ChapterFour/1200~1299/1249.Minimum-Remove-to-Make-Valid-Parentheses.md b/website/content/ChapterFour/1200~1299/1249.Minimum-Remove-to-Make-Valid-Parentheses.md
index 95889e34..c1936b88 100644
--- a/website/content/ChapterFour/1200~1299/1249.Minimum-Remove-to-Make-Valid-Parentheses.md
+++ b/website/content/ChapterFour/1200~1299/1249.Minimum-Remove-to-Make-Valid-Parentheses.md
@@ -97,6 +97,6 @@ func minRemoveToMakeValid(s string) string {
----------------------------------------------
diff --git a/website/content/ChapterTwo/Backtracking.md b/website/content/ChapterTwo/Backtracking.md
index 50b05478..f73366ed 100644
--- a/website/content/ChapterTwo/Backtracking.md
+++ b/website/content/ChapterTwo/Backtracking.md
@@ -130,6 +130,7 @@ func updateMatrix_BFS(matrix [][]int) [][]int {
|0980|Unique Paths III|[Go]({{< relref "/ChapterFour/0900~0999/0980.Unique-Paths-III.md" >}})|Hard| O(n log n)| O(n)||77.1%|
|0996|Number of Squareful Arrays|[Go]({{< relref "/ChapterFour/0900~0999/0996.Number-of-Squareful-Arrays.md" >}})|Hard| O(n log n)| O(n) ||48.6%|
|1079|Letter Tile Possibilities|[Go]({{< relref "/ChapterFour/1000~1099/1079.Letter-Tile-Possibilities.md" >}})|Medium| O(n^2)| O(1)|❤️|76.1%|
+|1239|Maximum Length of a Concatenated String with Unique Characters|[Go]({{< relref "/ChapterFour/1200~1299/1239.Maximum-Length-of-a-Concatenated-String-with-Unique-Characters.md" >}})|Medium||||50.5%|
|1641|Count Sorted Vowel Strings|[Go]({{< relref "/ChapterFour/1600~1699/1641.Count-Sorted-Vowel-Strings.md" >}})|Medium||||75.0%|
|1655|Distribute Repeating Integers|[Go]({{< relref "/ChapterFour/1600~1699/1655.Distribute-Repeating-Integers.md" >}})|Hard||||40.2%|
|1659|Maximize Grid Happiness|[Go]({{< relref "/ChapterFour/1600~1699/1659.Maximize-Grid-Happiness.md" >}})|Hard||||35.9%|
diff --git a/website/content/ChapterTwo/Bit_Manipulation.md b/website/content/ChapterTwo/Bit_Manipulation.md
index 4afca3f3..03fdd940 100644
--- a/website/content/ChapterTwo/Bit_Manipulation.md
+++ b/website/content/ChapterTwo/Bit_Manipulation.md
@@ -74,12 +74,13 @@ X & ~X = 0
|0784|Letter Case Permutation|[Go]({{< relref "/ChapterFour/0700~0799/0784.Letter-Case-Permutation.md" >}})|Medium| O(n)| O(1)||69.2%|
|0898|Bitwise ORs of Subarrays|[Go]({{< relref "/ChapterFour/0800~0899/0898.Bitwise-ORs-of-Subarrays.md" >}})|Medium| O(n)| O(1)||35.0%|
|1178|Number of Valid Words for Each Puzzle|[Go]({{< relref "/ChapterFour/1100~1199/1178.Number-of-Valid-Words-for-Each-Puzzle.md" >}})|Hard||||40.3%|
+|1239|Maximum Length of a Concatenated String with Unique Characters|[Go]({{< relref "/ChapterFour/1200~1299/1239.Maximum-Length-of-a-Concatenated-String-with-Unique-Characters.md" >}})|Medium||||50.5%|
|1290|Convert Binary Number in a Linked List to Integer|[Go]({{< relref "/ChapterFour/1200~1299/1290.Convert-Binary-Number-in-a-Linked-List-to-Integer.md" >}})|Easy||||81.7%|
|1310|XOR Queries of a Subarray|[Go]({{< relref "/ChapterFour/1300~1399/1310.XOR-Queries-of-a-Subarray.md" >}})|Medium||||69.8%|
|1442|Count Triplets That Can Form Two Arrays of Equal XOR|[Go]({{< relref "/ChapterFour/1400~1499/1442.Count-Triplets-That-Can-Form-Two-Arrays-of-Equal-XOR.md" >}})|Medium||||72.8%|
|1461|Check If a String Contains All Binary Codes of Size K|[Go]({{< relref "/ChapterFour/1400~1499/1461.Check-If-a-String-Contains-All-Binary-Codes-of-Size-K.md" >}})|Medium||||54.2%|
|1486|XOR Operation in an Array|[Go]({{< relref "/ChapterFour/1400~1499/1486.XOR-Operation-in-an-Array.md" >}})|Easy||||83.9%|
-|1720|Decode XORed Array|[Go]({{< relref "/ChapterFour/1700~1799/1720.Decode-XORed-Array.md" >}})|Easy||||85.5%|
+|1720|Decode XORed Array|[Go]({{< relref "/ChapterFour/1700~1799/1720.Decode-XORed-Array.md" >}})|Easy||||85.4%|
|1734|Decode XORed Permutation|[Go]({{< relref "/ChapterFour/1700~1799/1734.Decode-XORed-Permutation.md" >}})|Medium||||56.7%|
|------------|-------------------------------------------------------|-------| ----------------| ---------------|-------------|-------------|-------------|
diff --git a/website/content/ChapterTwo/Depth_First_Search.md b/website/content/ChapterTwo/Depth_First_Search.md
index 914e57b8..353d7a61 100644
--- a/website/content/ChapterTwo/Depth_First_Search.md
+++ b/website/content/ChapterTwo/Depth_First_Search.md
@@ -14,7 +14,7 @@ weight: 9
|0099|Recover Binary Search Tree|[Go]({{< relref "/ChapterFour/0001~0099/0099.Recover-Binary-Search-Tree.md" >}})|Medium| O(n)| O(1)||43.4%|
|0100|Same Tree|[Go]({{< relref "/ChapterFour/0100~0199/0100.Same-Tree.md" >}})|Easy| O(n)| O(1)||54.5%|
|0101|Symmetric Tree|[Go]({{< relref "/ChapterFour/0100~0199/0101.Symmetric-Tree.md" >}})|Easy| O(n)| O(1)||49.0%|
-|0104|Maximum Depth of Binary Tree|[Go]({{< relref "/ChapterFour/0100~0199/0104.Maximum-Depth-of-Binary-Tree.md" >}})|Easy| O(n)| O(1)||68.9%|
+|0104|Maximum Depth of Binary Tree|[Go]({{< relref "/ChapterFour/0100~0199/0104.Maximum-Depth-of-Binary-Tree.md" >}})|Easy| O(n)| O(1)||69.0%|
|0105|Construct Binary Tree from Preorder and Inorder Traversal|[Go]({{< relref "/ChapterFour/0100~0199/0105.Construct-Binary-Tree-from-Preorder-and-Inorder-Traversal.md" >}})|Medium||||53.8%|
|0106|Construct Binary Tree from Inorder and Postorder Traversal|[Go]({{< relref "/ChapterFour/0100~0199/0106.Construct-Binary-Tree-from-Inorder-and-Postorder-Traversal.md" >}})|Medium||||51.0%|
|0108|Convert Sorted Array to Binary Search Tree|[Go]({{< relref "/ChapterFour/0100~0199/0108.Convert-Sorted-Array-to-Binary-Search-Tree.md" >}})|Easy| O(n)| O(1)||61.8%|
diff --git a/website/content/ChapterTwo/Math.md b/website/content/ChapterTwo/Math.md
index 3d727455..f22e919f 100644
--- a/website/content/ChapterTwo/Math.md
+++ b/website/content/ChapterTwo/Math.md
@@ -84,7 +84,7 @@ weight: 12
|1017|Convert to Base -2|[Go]({{< relref "/ChapterFour/1000~1099/1017.Convert-to-Base-2.md" >}})|Medium||||59.4%|
|1025|Divisor Game|[Go]({{< relref "/ChapterFour/1000~1099/1025.Divisor-Game.md" >}})|Easy| O(1)| O(1)||66.2%|
|1037|Valid Boomerang|[Go]({{< relref "/ChapterFour/1000~1099/1037.Valid-Boomerang.md" >}})|Easy||||37.4%|
-|1073|Adding Two Negabinary Numbers|[Go]({{< relref "/ChapterFour/1000~1099/1073.Adding-Two-Negabinary-Numbers.md" >}})|Medium||||34.7%|
+|1073|Adding Two Negabinary Numbers|[Go]({{< relref "/ChapterFour/1000~1099/1073.Adding-Two-Negabinary-Numbers.md" >}})|Medium||||34.8%|
|1093|Statistics from a Large Sample|[Go]({{< relref "/ChapterFour/1000~1099/1093.Statistics-from-a-Large-Sample.md" >}})|Medium||||47.8%|
|1154|Day of the Year|[Go]({{< relref "/ChapterFour/1100~1199/1154.Day-of-the-Year.md" >}})|Easy||||49.6%|
|1175|Prime Arrangements|[Go]({{< relref "/ChapterFour/1100~1199/1175.Prime-Arrangements.md" >}})|Easy||||51.8%|
@@ -100,7 +100,7 @@ weight: 12
|1648|Sell Diminishing-Valued Colored Balls|[Go]({{< relref "/ChapterFour/1600~1699/1648.Sell-Diminishing-Valued-Colored-Balls.md" >}})|Medium||||31.1%|
|1680|Concatenation of Consecutive Binary Numbers|[Go]({{< relref "/ChapterFour/1600~1699/1680.Concatenation-of-Consecutive-Binary-Numbers.md" >}})|Medium||||52.2%|
|1685|Sum of Absolute Differences in a Sorted Array|[Go]({{< relref "/ChapterFour/1600~1699/1685.Sum-of-Absolute-Differences-in-a-Sorted-Array.md" >}})|Medium||||63.4%|
-|1716|Calculate Money in Leetcode Bank|[Go]({{< relref "/ChapterFour/1700~1799/1716.Calculate-Money-in-Leetcode-Bank.md" >}})|Easy||||64.0%|
+|1716|Calculate Money in Leetcode Bank|[Go]({{< relref "/ChapterFour/1700~1799/1716.Calculate-Money-in-Leetcode-Bank.md" >}})|Easy||||64.1%|
|1744|Can You Eat Your Favorite Candy on Your Favorite Day?|[Go]({{< relref "/ChapterFour/1700~1799/1744.Can-You-Eat-Your-Favorite-Candy-on-Your-Favorite-Day.md" >}})|Medium||||31.3%|
|------------|-------------------------------------------------------|-------| ----------------| ---------------|-------------|-------------|-------------|
diff --git a/website/content/ChapterTwo/Tree.md b/website/content/ChapterTwo/Tree.md
index b7516b5c..6bbe5ba3 100644
--- a/website/content/ChapterTwo/Tree.md
+++ b/website/content/ChapterTwo/Tree.md
@@ -18,7 +18,7 @@ weight: 6
|0101|Symmetric Tree|[Go]({{< relref "/ChapterFour/0100~0199/0101.Symmetric-Tree.md" >}})|Easy| O(n)| O(1)||49.0%|
|0102|Binary Tree Level Order Traversal|[Go]({{< relref "/ChapterFour/0100~0199/0102.Binary-Tree-Level-Order-Traversal.md" >}})|Medium| O(n)| O(1)||57.9%|
|0103|Binary Tree Zigzag Level Order Traversal|[Go]({{< relref "/ChapterFour/0100~0199/0103.Binary-Tree-Zigzag-Level-Order-Traversal.md" >}})|Medium| O(n)| O(n)||51.0%|
-|0104|Maximum Depth of Binary Tree|[Go]({{< relref "/ChapterFour/0100~0199/0104.Maximum-Depth-of-Binary-Tree.md" >}})|Easy| O(n)| O(1)||68.9%|
+|0104|Maximum Depth of Binary Tree|[Go]({{< relref "/ChapterFour/0100~0199/0104.Maximum-Depth-of-Binary-Tree.md" >}})|Easy| O(n)| O(1)||69.0%|
|0105|Construct Binary Tree from Preorder and Inorder Traversal|[Go]({{< relref "/ChapterFour/0100~0199/0105.Construct-Binary-Tree-from-Preorder-and-Inorder-Traversal.md" >}})|Medium||||53.8%|
|0106|Construct Binary Tree from Inorder and Postorder Traversal|[Go]({{< relref "/ChapterFour/0100~0199/0106.Construct-Binary-Tree-from-Inorder-and-Postorder-Traversal.md" >}})|Medium||||51.0%|
|0107|Binary Tree Level Order Traversal II|[Go]({{< relref "/ChapterFour/0100~0199/0107.Binary-Tree-Level-Order-Traversal-II.md" >}})|Medium| O(n)| O(1)||56.1%|