Update solution 0018

2025-07-05 08:27:30 +08:00 · 2021-07-27 21:21:21 +08:00
parent ae5c145c3f
commit 3755d3f251
8 changed files with 212 additions and 39 deletions
--- a/README.md
+++ b/README.md
@ -324,7 +324,7 @@
 |0183|Customers Who Never Order||59.3%|Easy||
 |0184|Department Highest Salary||42.7%|Medium||
 |0185|Department Top Three Salaries||42.3%|Hard||
-|0186|Reverse Words in a String II||48.2%|Medium||
+|0186|Reverse Words in a String II||48.3%|Medium||
 |0187|Repeated DNA Sequences|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0187.Repeated-DNA-Sequences)|42.4%|Medium||
 |0188|Best Time to Buy and Sell Stock IV||31.1%|Hard||
 |0189|Rotate Array|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0189.Rotate-Array)|36.8%|Medium||
@ -387,7 +387,7 @@
 |0246|Strobogrammatic Number||46.9%|Easy||
 |0247|Strobogrammatic Number II||49.4%|Medium||
 |0248|Strobogrammatic Number III||40.7%|Hard||
-|0249|Group Shifted Strings||59.5%|Medium||
+|0249|Group Shifted Strings||59.6%|Medium||
 |0250|Count Univalue Subtrees||53.8%|Medium||
 |0251|Flatten 2D Vector||46.8%|Medium||
 |0252|Meeting Rooms||55.9%|Easy||
@ -605,7 +605,7 @@
 |0464|Can I Win||29.7%|Medium||
 |0465|Optimal Account Balancing||48.7%|Hard||
 |0466|Count The Repetitions||28.7%|Hard||
-|0467|Unique Substrings in Wraparound String||36.7%|Medium||
+|0467|Unique Substrings in Wraparound String||36.6%|Medium||
 |0468|Validate IP Address||25.5%|Medium||
 |0469|Convex Polygon||37.8%|Medium||
 |0470|Implement Rand10() Using Rand7()|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0470.Implement-Rand10-Using-Rand7)|46.2%|Medium||
@ -633,11 +633,11 @@
 |0492|Construct the Rectangle||51.3%|Easy||
 |0493|Reverse Pairs|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0493.Reverse-Pairs)|28.2%|Hard||
 |0494|Target Sum|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0494.Target-Sum)|45.4%|Medium||
-|0495|Teemo Attacking||56.2%|Easy||
+|0495|Teemo Attacking||56.3%|Easy||
 |0496|Next Greater Element I|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0496.Next-Greater-Element-I)|66.9%|Easy||
 |0497|Random Point in Non-overlapping Rectangles|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0497.Random-Point-in-Non-overlapping-Rectangles)|39.1%|Medium||
 |0498|Diagonal Traverse|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0498.Diagonal-Traverse)|52.0%|Medium||
-|0499|The Maze III||43.2%|Hard||
+|0499|The Maze III||43.3%|Hard||
 |0500|Keyboard Row|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0500.Keyboard-Row)|66.6%|Easy||
 |0501|Find Mode in Binary Search Tree||44.9%|Easy||
 |0502|IPO||42.4%|Hard||
@ -684,7 +684,7 @@
 |0543|Diameter of Binary Tree|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0543.Diameter-of-Binary-Tree)|50.9%|Easy||
 |0544|Output Contest Matches||76.2%|Medium||
 |0545|Boundary of Binary Tree||41.4%|Medium||
-|0546|Remove Boxes||44.3%|Hard||
+|0546|Remove Boxes||44.4%|Hard||
 |0547|Number of Provinces|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0547.Number-of-Provinces)|61.7%|Medium||
 |0548|Split Array with Equal Sum||49.4%|Hard||
 |0549|Binary Tree Longest Consecutive Sequence II||48.1%|Medium||
@ -735,7 +735,7 @@
 |0594|Longest Harmonious Subsequence|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0594.Longest-Harmonious-Subsequence)|51.7%|Easy||
 |0595|Big Countries||79.2%|Easy||
 |0596|Classes More Than 5 Students||39.2%|Easy||
-|0597|Friend Requests I: Overall Acceptance Rate||42.2%|Easy||
+|0597|Friend Requests I: Overall Acceptance Rate||42.3%|Easy||
 |0598|Range Addition II|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0598.Range-Addition-II)|50.7%|Easy||
 |0599|Minimum Index Sum of Two Lists|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0599.Minimum-Index-Sum-of-Two-Lists)|52.5%|Easy||
 |0600|Non-negative Integers without Consecutive Ones||38.1%|Hard||
@ -1192,7 +1192,7 @@
 |1051|Height Checker|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1051.Height-Checker)|73.3%|Easy||
 |1052|Grumpy Bookstore Owner|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1052.Grumpy-Bookstore-Owner)|56.1%|Medium||
 |1053|Previous Permutation With One Swap||52.0%|Medium||
-|1054|Distant Barcodes|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1054.Distant-Barcodes)|44.7%|Medium||
+|1054|Distant Barcodes|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1054.Distant-Barcodes)|44.8%|Medium||
 |1055|Shortest Way to Form String||57.6%|Medium||
 |1056|Confusing Number||46.5%|Easy||
 |1057|Campus Bikes||58.0%|Medium||
@ -1201,7 +1201,7 @@
 |1060|Missing Element in Sorted Array||55.3%|Medium||
 |1061|Lexicographically Smallest Equivalent String||67.1%|Medium||
 |1062|Longest Repeating Substring||58.9%|Medium||
-|1063|Number of Valid Subarrays||72.4%|Hard||
+|1063|Number of Valid Subarrays||72.5%|Hard||
 |1064|Fixed Point||64.0%|Easy||
 |1065|Index Pairs of a String||61.2%|Easy||
 |1066|Campus Bikes II||54.4%|Medium||
@ -1311,7 +1311,7 @@
 |1170|Compare Strings by Frequency of the Smallest Character|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1170.Compare-Strings-by-Frequency-of-the-Smallest-Character)|60.6%|Medium||
 |1171|Remove Zero Sum Consecutive Nodes from Linked List|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1171.Remove-Zero-Sum-Consecutive-Nodes-from-Linked-List)|41.8%|Medium||
 |1172|Dinner Plate Stacks||36.4%|Hard||
-|1173|Immediate Food Delivery I||83.1%|Easy||
+|1173|Immediate Food Delivery I||83.0%|Easy||
 |1174|Immediate Food Delivery II||63.0%|Medium||
 |1175|Prime Arrangements|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1175.Prime-Arrangements)|51.8%|Easy||
 |1176|Diet Plan Performance||53.5%|Easy||
@ -1638,7 +1638,7 @@
 |1497|Check If Array Pairs Are Divisible by k||40.3%|Medium||
 |1498|Number of Subsequences That Satisfy the Given Sum Condition||39.4%|Medium||
 |1499|Max Value of Equation||46.0%|Hard||
-|1500|Design a File Sharing System||46.7%|Medium||
+|1500|Design a File Sharing System||46.6%|Medium||
 |1501|Countries You Can Safely Invest In||59.8%|Medium||
 |1502|Can Make Arithmetic Progression From Sequence||70.3%|Easy||
 |1503|Last Moment Before All Ants Fall Out of a Plank||53.9%|Medium||
@ -1782,7 +1782,7 @@
 |1641|Count Sorted Vowel Strings|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1641.Count-Sorted-Vowel-Strings)|75.0%|Medium||
 |1642|Furthest Building You Can Reach|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1642.Furthest-Building-You-Can-Reach)|43.5%|Medium||
 |1643|Kth Smallest Instructions||45.3%|Hard||
-|1644|Lowest Common Ancestor of a Binary Tree II||57.2%|Medium||
+|1644|Lowest Common Ancestor of a Binary Tree II||57.3%|Medium||
 |1645|Hopper Company Queries II||39.3%|Hard||
 |1646|Get Maximum in Generated Array|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1646.Get-Maximum-in-Generated-Array)|52.2%|Easy||
 |1647|Minimum Deletions to Make Character Frequencies Unique|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1647.Minimum-Deletions-to-Make-Character-Frequencies-Unique)|55.8%|Medium||
@ -1803,7 +1803,7 @@
 |1662|Check If Two String Arrays are Equivalent|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1662.Check-If-Two-String-Arrays-are-Equivalent)|82.0%|Easy||
 |1663|Smallest String With A Given Numeric Value|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1663.Smallest-String-With-A-Given-Numeric-Value)|64.3%|Medium||
 |1664|Ways to Make a Fair Array|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1664.Ways-to-Make-a-Fair-Array)|62.1%|Medium||
-|1665|Minimum Initial Energy to Finish Tasks|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1665.Minimum-Initial-Energy-to-Finish-Tasks)|55.1%|Hard||
+|1665|Minimum Initial Energy to Finish Tasks|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1665.Minimum-Initial-Energy-to-Finish-Tasks)|55.0%|Hard||
 |1666|Change the Root of a Binary Tree||65.4%|Medium||
 |1667|Fix Names in a Table||62.2%|Easy||
 |1668|Maximum Repeating Substring|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1668.Maximum-Repeating-Substring)|38.8%|Easy||
@ -1829,7 +1829,7 @@
 |1688|Count of Matches in Tournament|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1688.Count-of-Matches-in-Tournament)|82.1%|Easy||
 |1689|Partitioning Into Minimum Number Of Deci-Binary Numbers|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1689.Partitioning-Into-Minimum-Number-Of-Deci-Binary-Numbers)|88.0%|Medium||
 |1690|Stone Game VII|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1690.Stone-Game-VII)|58.7%|Medium||
-|1691|Maximum Height by Stacking Cuboids|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1691.Maximum-Height-by-Stacking-Cuboids)|51.1%|Hard||
+|1691|Maximum Height by Stacking Cuboids|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1691.Maximum-Height-by-Stacking-Cuboids)|51.2%|Hard||
 |1692|Count Ways to Distribute Candies||60.2%|Hard||
 |1693|Daily Leads and Partners||90.9%|Easy||
 |1694|Reformat Phone Number|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1694.Reformat-Phone-Number)|64.8%|Easy||
@ -1840,7 +1840,7 @@
 |1699|Number of Calls Between Two Persons||86.0%|Medium||
 |1700|Number of Students Unable to Eat Lunch|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1700.Number-of-Students-Unable-to-Eat-Lunch)|67.7%|Easy||
 |1701|Average Waiting Time||60.8%|Medium||
-|1702|Maximum Binary String After Change||44.2%|Medium||
+|1702|Maximum Binary String After Change||44.3%|Medium||
 |1703|Minimum Adjacent Swaps for K Consecutive Ones||37.6%|Hard||
 |1704|Determine if String Halves Are Alike|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1704.Determine-if-String-Halves-Are-Alike)|78.5%|Easy||
 |1705|Maximum Number of Eaten Apples||34.8%|Medium||
@ -1895,7 +1895,7 @@
 |1754|Largest Merge Of Two Strings||42.2%|Medium||
 |1755|Closest Subsequence Sum||34.5%|Hard||
 |1756|Design Most Recently Used Queue||78.0%|Medium||
-|1757|Recyclable and Low Fat Products||95.5%|Easy||
+|1757|Recyclable and Low Fat Products||95.4%|Easy||
 |1758|Minimum Changes To Make Alternating Binary String|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1758.Minimum-Changes-To-Make-Alternating-Binary-String)|58.7%|Easy||
 |1759|Count Number of Homogenous Substrings||44.0%|Medium||
 |1760|Minimum Limit of Balls in a Bag||54.5%|Medium||
@ -1942,14 +1942,14 @@
 |1801|Number of Orders in the Backlog||44.6%|Medium||
 |1802|Maximum Value at a Given Index in a Bounded Array||28.6%|Medium||
 |1803|Count Pairs With XOR in a Range||45.4%|Hard||
-|1804|Implement Trie II (Prefix Tree)||58.3%|Medium||
+|1804|Implement Trie II (Prefix Tree)||58.4%|Medium||
 |1805|Number of Different Integers in a String||34.9%|Easy||
 |1806|Minimum Number of Operations to Reinitialize a Permutation||70.3%|Medium||
 |1807|Evaluate the Bracket Pairs of a String||66.5%|Medium||
 |1808|Maximize Number of Nice Divisors||28.5%|Hard||
 |1809|Ad-Free Sessions||62.1%|Easy||
 |1810|Minimum Path Cost in a Hidden Grid||54.0%|Medium||
-|1811|Find Interview Candidates||66.4%|Medium||
+|1811|Find Interview Candidates||66.5%|Medium||
 |1812|Determine Color of a Chessboard Square||77.0%|Easy||
 |1813|Sentence Similarity III||31.6%|Medium||
 |1814|Count Nice Pairs in an Array||39.3%|Medium||
@ -1982,7 +1982,7 @@
 |1841|League Statistics||61.8%|Medium||
 |1842|Next Palindrome Using Same Digits||62.8%|Hard||
 |1843|Suspicious Bank Accounts||51.5%|Medium||
-|1844|Replace All Digits with Characters||80.0%|Easy||
+|1844|Replace All Digits with Characters||80.1%|Easy||
 |1845|Seat Reservation Manager||56.4%|Medium||
 |1846|Maximum Element After Decreasing and Rearranging|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/1846.Maximum-Element-After-Decreasing-and-Rearranging)|55.4%|Medium||
 |1847|Closest Room||31.9%|Hard||
@ -1992,11 +1992,11 @@
 |1851|Minimum Interval to Include Each Query||43.9%|Hard||
 |1852|Distinct Numbers in Each Subarray||75.3%|Medium||
 |1853|Convert Date Format||89.1%|Easy||
-|1854|Maximum Population Year||57.6%|Easy||
+|1854|Maximum Population Year||57.7%|Easy||
 |1855|Maximum Distance Between a Pair of Values||46.5%|Medium||
 |1856|Maximum Subarray Min-Product||33.6%|Medium||
 |1857|Largest Color Value in a Directed Graph||37.4%|Hard||
-|1858|Longest Word With All Prefixes||65.6%|Medium||
+|1858|Longest Word With All Prefixes||65.5%|Medium||
 |1859|Sorting the Sentence||83.1%|Easy||
 |1860|Incremental Memory Leak||69.5%|Medium||
 |1861|Rotating the Box||62.6%|Medium||
@ -2033,7 +2033,7 @@
 |1892|Page Recommendations II||44.0%|Hard||
 |1893|Check if All the Integers in a Range Are Covered||50.0%|Easy||
 |1894|Find the Student that Will Replace the Chalk||39.2%|Medium||
-|1895|Largest Magic Square||49.7%|Medium||
+|1895|Largest Magic Square||49.8%|Medium||
 |1896|Minimum Cost to Change the Final Value of Expression||51.6%|Hard||
 |1897|Redistribute Characters to Make All Strings Equal||59.4%|Easy||
 |1898|Maximum Number of Removable Characters||33.1%|Medium||
@ -2047,7 +2047,7 @@
 |1906|Minimum Absolute Difference Queries||42.0%|Medium||
 |1907|Count Salary Categories||67.9%|Medium||
 |1908|Game of Nim||64.9%|Medium||
-|1909|Remove One Element to Make the Array Strictly Increasing||30.6%|Easy||
+|1909|Remove One Element to Make the Array Strictly Increasing||30.7%|Easy||
 |1910|Remove All Occurrences of a Substring||72.3%|Medium||
 |1911|Maximum Alternating Subsequence Sum||57.5%|Medium||
 |1912|Design Movie Rental System||42.2%|Hard||
@ -2056,7 +2056,7 @@
 |1915|Number of Wonderful Substrings||38.5%|Medium||
 |1916|Count Ways to Build Rooms in an Ant Colony||50.1%|Hard||
 |1917|Leetcodify Friends Recommendations||32.2%|Hard||
-|1918|Kth Smallest Subarray Sum||56.1%|Medium||
+|1918|Kth Smallest Subarray Sum||56.0%|Medium||
 |1919|Leetcodify Similar Friends||44.2%|Hard||
 |1920|Build Array from Permutation||93.8%|Easy||
 |1921|Eliminate Maximum Number of Monsters||37.4%|Medium||
@ -2079,22 +2079,22 @@
 |1938|Maximum Genetic Difference Query||37.7%|Hard||
 |1939|Users That Actively Request Confirmation Messages||68.7%|Easy||
 |1940|Longest Common Subsequence Between Sorted Arrays||84.1%|Medium||
-|1941|Check if All Characters Have Equal Number of Occurrences||77.1%|Easy||
-|1942|The Number of the Smallest Unoccupied Chair||35.9%|Medium||
+|1941|Check if All Characters Have Equal Number of Occurrences||77.0%|Easy||
+|1942|The Number of the Smallest Unoccupied Chair||36.0%|Medium||
 |1943|Describe the Painting||44.3%|Medium||
 |1944|Number of Visible People in a Queue||61.2%|Hard||
 |1945|Sum of Digits of String After Convert||62.3%|Easy||
 |1946|Largest Number After Mutating Substring||32.6%|Medium||
 |1947|Maximum Compatibility Score Sum||56.9%|Medium||
 |1948|Delete Duplicate Folders in System||61.9%|Hard||
-|1949|Strong Friendship||63.1%|Medium||
-|1950|Maximum of Minimum Values in All Subarrays||52.4%|Medium||
-|1951|All the Pairs With the Maximum Number of Common Followers||78.7%|Medium||
+|1949|Strong Friendship||62.7%|Medium||
+|1950|Maximum of Minimum Values in All Subarrays||52.8%|Medium||
+|1951|All the Pairs With the Maximum Number of Common Followers||78.8%|Medium||
 |1952|Three Divisors||55.8%|Easy||
 |1953|Maximum Number of Weeks for Which You Can Work||33.5%|Medium||
 |1954|Minimum Garden Perimeter to Collect Enough Apples||52.0%|Medium||
 |1955|Count Number of Special Subsequences||49.5%|Hard||
-|1956|Minimum Time For K Virus Variants to Spread||46.4%|Hard||
+|1956|Minimum Time For K Virus Variants to Spread||46.3%|Hard||
 |------------|-------------------------------------------------------|-------| ----------------| ---------------|-------------|

 ------------------------------------------------------------------
--- a/leetcode/0018.4Sum/18.
+++ b/leetcode/0018.4Sum/18.
@ -2,7 +2,92 @@ package leetcode

 import "sort"

-func fourSum(nums []int, target int) [][]int {
+// 解法一 双指针
+func fourSum(nums []int, target int) (quadruplets [][]int) {
+	sort.Ints(nums)
+	n := len(nums)
+	for i := 0; i < n-3 && nums[i]+nums[i+1]+nums[i+2]+nums[i+3] <= target; i++ {
+		if i > 0 && nums[i] == nums[i-1] || nums[i]+nums[n-3]+nums[n-2]+nums[n-1] < target {
+			continue
+		}
+		for j := i + 1; j < n-2 && nums[i]+nums[j]+nums[j+1]+nums[j+2] <= target; j++ {
+			if j > i+1 && nums[j] == nums[j-1] || nums[i]+nums[j]+nums[n-2]+nums[n-1] < target {
+				continue
+			}
+			for left, right := j+1, n-1; left < right; {
+				if sum := nums[i] + nums[j] + nums[left] + nums[right]; sum == target {
+					quadruplets = append(quadruplets, []int{nums[i], nums[j], nums[left], nums[right]})
+					for left++; left < right && nums[left] == nums[left-1]; left++ {
+					}
+					for right--; left < right && nums[right] == nums[right+1]; right-- {
+					}
+				} else if sum < target {
+					left++
+				} else {
+					right--
+				}
+			}
+		}
+	}
+	return
+}
+
+// 解法二 kSum
+func fourSum1(nums []int, target int) [][]int {
+	res, cur := make([][]int, 0), make([]int, 0)
+	sort.Ints(nums)
+	kSum(nums, 0, len(nums)-1, target, 4, cur, &res)
+	return res
+}
+
+func kSum(nums []int, left, right int, target int, k int, cur []int, res *[][]int) {
+	if right-left+1 < k || k < 2 || target < nums[left]*k || target > nums[right]*k {
+		return
+	}
+	if k == 2 {
+		// 2 sum
+		twoSum(nums, left, right, target, cur, res)
+	} else {
+		for i := left; i < len(nums); i++ {
+			if i == left || (i > left && nums[i-1] != nums[i]) {
+				next := make([]int, len(cur))
+				copy(next, cur)
+				next = append(next, nums[i])
+				kSum(nums, i+1, len(nums)-1, target-nums[i], k-1, next, res)
+			}
+		}
+	}
+
+}
+
+func twoSum(nums []int, left, right int, target int, cur []int, res *[][]int) {
+	for left < right {
+		sum := nums[left] + nums[right]
+		if sum == target {
+			cur = append(cur, nums[left], nums[right])
+			temp := make([]int, len(cur))
+			copy(temp, cur)
+			*res = append(*res, temp)
+			// reset cur to previous state
+			cur = cur[:len(cur)-2]
+			left++
+			right--
+			for left < right && nums[left] == nums[left-1] {
+				left++
+			}
+			for left < right && nums[right] == nums[right+1] {
+				right--
+			}
+		} else if sum < target {
+			left++
+		} else {
+			right--
+		}
+	}
+}
+
+// 解法三
+func fourSum2(nums []int, target int) [][]int {
 	res := [][]int{}
 	counter := map[int]int{}
 	for _, value := range nums {
--- a/website/content/ChapterFour/0001~0099/0018.4Sum.md
+++ b/website/content/ChapterFour/0001~0099/0018.4Sum.md
@ -44,7 +44,92 @@ package leetcode

 import "sort"

-func fourSum(nums []int, target int) [][]int {
+// 解法一 双指针
+func fourSum(nums []int, target int) (quadruplets [][]int) {
+	sort.Ints(nums)
+	n := len(nums)
+	for i := 0; i < n-3 && nums[i]+nums[i+1]+nums[i+2]+nums[i+3] <= target; i++ {
+		if i > 0 && nums[i] == nums[i-1] || nums[i]+nums[n-3]+nums[n-2]+nums[n-1] < target {
+			continue
+		}
+		for j := i + 1; j < n-2 && nums[i]+nums[j]+nums[j+1]+nums[j+2] <= target; j++ {
+			if j > i+1 && nums[j] == nums[j-1] || nums[i]+nums[j]+nums[n-2]+nums[n-1] < target {
+				continue
+			}
+			for left, right := j+1, n-1; left < right; {
+				if sum := nums[i] + nums[j] + nums[left] + nums[right]; sum == target {
+					quadruplets = append(quadruplets, []int{nums[i], nums[j], nums[left], nums[right]})
+					for left++; left < right && nums[left] == nums[left-1]; left++ {
+					}
+					for right--; left < right && nums[right] == nums[right+1]; right-- {
+					}
+				} else if sum < target {
+					left++
+				} else {
+					right--
+				}
+			}
+		}
+	}
+	return
+}
+
+// 解法二 kSum
+func fourSum1(nums []int, target int) [][]int {
+	res, cur := make([][]int, 0), make([]int, 0)
+	sort.Ints(nums)
+	kSum(nums, 0, len(nums)-1, target, 4, cur, &res)
+	return res
+}
+
+func kSum(nums []int, left, right int, target int, k int, cur []int, res *[][]int) {
+	if right-left+1 < k || k < 2 || target < nums[left]*k || target > nums[right]*k {
+		return
+	}
+	if k == 2 {
+		// 2 sum
+		twoSum(nums, left, right, target, cur, res)
+	} else {
+		for i := left; i < len(nums); i++ {
+			if i == left || (i > left && nums[i-1] != nums[i]) {
+				next := make([]int, len(cur))
+				copy(next, cur)
+				next = append(next, nums[i])
+				kSum(nums, i+1, len(nums)-1, target-nums[i], k-1, next, res)
+			}
+		}
+	}
+
+}
+
+func twoSum(nums []int, left, right int, target int, cur []int, res *[][]int) {
+	for left < right {
+		sum := nums[left] + nums[right]
+		if sum == target {
+			cur = append(cur, nums[left], nums[right])
+			temp := make([]int, len(cur))
+			copy(temp, cur)
+			*res = append(*res, temp)
+			// reset cur to previous state
+			cur = cur[:len(cur)-2]
+			left++
+			right--
+			for left < right && nums[left] == nums[left-1] {
+				left++
+			}
+			for left < right && nums[right] == nums[right+1] {
+				right--
+			}
+		} else if sum < target {
+			left++
+		} else {
+			right--
+		}
+	}
+}
+
+// 解法三
+func fourSum2(nums []int, target int) [][]int {
 	res := [][]int{}
 	counter := map[int]int{}
 	for _, value := range nums {
--- a/website/content/ChapterFour/1800~1899/1877.Minimize-Maximum-Pair-Sum-in-Array.md
+++ b/website/content/ChapterFour/1800~1899/1877.Minimize-Maximum-Pair-Sum-in-Array.md
@ -14,5 +14,8 @@

 ```

+
+
 ----------------------------------------------
 <p><a href="https://books.halfrost.com/leetcode/ChapterFour/1800~1899/1846.Maximum-Element-After-Decreasing-and-Rearranging/">⬅️上一页</a></p>
+
--- a/website/content/ChapterTwo/Array.md
+++ b/website/content/ChapterTwo/Array.md
@ -355,7 +355,7 @@ weight: 1
 |1658|Minimum Operations to Reduce X to Zero|[Go]({{< relref "/ChapterFour/1600~1699/1658.Minimum-Operations-to-Reduce-X-to-Zero.md" >}})|Medium||||33.3%|
 |1662|Check If Two String Arrays are Equivalent|[Go]({{< relref "/ChapterFour/1600~1699/1662.Check-If-Two-String-Arrays-are-Equivalent.md" >}})|Easy||||82.0%|
 |1664|Ways to Make a Fair Array|[Go]({{< relref "/ChapterFour/1600~1699/1664.Ways-to-Make-a-Fair-Array.md" >}})|Medium||||62.1%|
-|1665|Minimum Initial Energy to Finish Tasks|[Go]({{< relref "/ChapterFour/1600~1699/1665.Minimum-Initial-Energy-to-Finish-Tasks.md" >}})|Hard||||55.1%|
+|1665|Minimum Initial Energy to Finish Tasks|[Go]({{< relref "/ChapterFour/1600~1699/1665.Minimum-Initial-Energy-to-Finish-Tasks.md" >}})|Hard||||55.0%|
 |1670|Design Front Middle Back Queue|[Go]({{< relref "/ChapterFour/1600~1699/1670.Design-Front-Middle-Back-Queue.md" >}})|Medium||||54.7%|
 |1672|Richest Customer Wealth|[Go]({{< relref "/ChapterFour/1600~1699/1672.Richest-Customer-Wealth.md" >}})|Easy||||88.2%|
 |1673|Find the Most Competitive Subsequence|[Go]({{< relref "/ChapterFour/1600~1699/1673.Find-the-Most-Competitive-Subsequence.md" >}})|Medium||||46.4%|
@ -366,7 +366,7 @@ weight: 1
 |1684|Count the Number of Consistent Strings|[Go]({{< relref "/ChapterFour/1600~1699/1684.Count-the-Number-of-Consistent-Strings.md" >}})|Easy||||81.8%|
 |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||||63.8%|
 |1690|Stone Game VII|[Go]({{< relref "/ChapterFour/1600~1699/1690.Stone-Game-VII.md" >}})|Medium||||58.7%|
-|1691|Maximum Height by Stacking Cuboids|[Go]({{< relref "/ChapterFour/1600~1699/1691.Maximum-Height-by-Stacking-Cuboids.md" >}})|Hard||||51.1%|
+|1691|Maximum Height by Stacking Cuboids|[Go]({{< relref "/ChapterFour/1600~1699/1691.Maximum-Height-by-Stacking-Cuboids.md" >}})|Hard||||51.2%|
 |1695|Maximum Erasure Value|[Go]({{< relref "/ChapterFour/1600~1699/1695.Maximum-Erasure-Value.md" >}})|Medium||||52.3%|
 |1696|Jump Game VI|[Go]({{< relref "/ChapterFour/1600~1699/1696.Jump-Game-VI.md" >}})|Medium||||41.9%|
 |1700|Number of Students Unable to Eat Lunch|[Go]({{< relref "/ChapterFour/1700~1799/1700.Number-of-Students-Unable-to-Eat-Lunch.md" >}})|Easy||||67.7%|
--- a/website/content/ChapterTwo/Binary_Search.md
+++ b/website/content/ChapterTwo/Binary_Search.md
@ -170,7 +170,7 @@ func peakIndexInMountainArray(A []int) int {
 |0611|Valid Triangle Number|[Go]({{< relref "/ChapterFour/0600~0699/0611.Valid-Triangle-Number.md" >}})|Medium||||49.0%|
 |0633|Sum of Square Numbers|[Go]({{< relref "/ChapterFour/0600~0699/0633.Sum-of-Square-Numbers.md" >}})|Medium||||33.0%|
 |0658|Find K Closest Elements|[Go]({{< relref "/ChapterFour/0600~0699/0658.Find-K-Closest-Elements.md" >}})|Medium||||43.3%|
-|0668|Kth Smallest Number in Multiplication Table|[Go]({{< relref "/ChapterFour/0600~0699/0668.Kth-Smallest-Number-in-Multiplication-Table.md" >}})|Hard||||48.5%|
+|0668|Kth Smallest Number in Multiplication Table|[Go]({{< relref "/ChapterFour/0600~0699/0668.Kth-Smallest-Number-in-Multiplication-Table.md" >}})|Hard||||48.4%|
 |0704|Binary Search|[Go]({{< relref "/ChapterFour/0700~0799/0704.Binary-Search.md" >}})|Easy||||54.9%|
 |0710|Random Pick with Blacklist|[Go]({{< relref "/ChapterFour/0700~0799/0710.Random-Pick-with-Blacklist.md" >}})|Hard| O(n)| O(n)  ||33.3%|
 |0718|Maximum Length of Repeated Subarray|[Go]({{< relref "/ChapterFour/0700~0799/0718.Maximum-Length-of-Repeated-Subarray.md" >}})|Medium||||51.1%|
--- a/website/content/ChapterTwo/Dynamic_Programming.md
+++ b/website/content/ChapterTwo/Dynamic_Programming.md
@ -101,7 +101,7 @@ weight: 7
 |1664|Ways to Make a Fair Array|[Go]({{< relref "/ChapterFour/1600~1699/1664.Ways-to-Make-a-Fair-Array.md" >}})|Medium||||62.1%|
 |1681|Minimum Incompatibility|[Go]({{< relref "/ChapterFour/1600~1699/1681.Minimum-Incompatibility.md" >}})|Hard||||36.1%|
 |1690|Stone Game VII|[Go]({{< relref "/ChapterFour/1600~1699/1690.Stone-Game-VII.md" >}})|Medium||||58.7%|
-|1691|Maximum Height by Stacking Cuboids|[Go]({{< relref "/ChapterFour/1600~1699/1691.Maximum-Height-by-Stacking-Cuboids.md" >}})|Hard||||51.1%|
+|1691|Maximum Height by Stacking Cuboids|[Go]({{< relref "/ChapterFour/1600~1699/1691.Maximum-Height-by-Stacking-Cuboids.md" >}})|Hard||||51.2%|
 |1696|Jump Game VI|[Go]({{< relref "/ChapterFour/1600~1699/1696.Jump-Game-VI.md" >}})|Medium||||41.9%|
 |------------|-------------------------------------------------------|-------| ----------------| ---------------|-------------|-------------|-------------|

--- a/website/content/ChapterTwo/Sorting.md
+++ b/website/content/ChapterTwo/Sorting.md
@ -106,9 +106,9 @@ weight: 14
 |1647|Minimum Deletions to Make Character Frequencies Unique|[Go]({{< relref "/ChapterFour/1600~1699/1647.Minimum-Deletions-to-Make-Character-Frequencies-Unique.md" >}})|Medium||||55.8%|
 |1648|Sell Diminishing-Valued Colored Balls|[Go]({{< relref "/ChapterFour/1600~1699/1648.Sell-Diminishing-Valued-Colored-Balls.md" >}})|Medium||||31.4%|
 |1657|Determine if Two Strings Are Close|[Go]({{< relref "/ChapterFour/1600~1699/1657.Determine-if-Two-Strings-Are-Close.md" >}})|Medium||||54.8%|
-|1665|Minimum Initial Energy to Finish Tasks|[Go]({{< relref "/ChapterFour/1600~1699/1665.Minimum-Initial-Energy-to-Finish-Tasks.md" >}})|Hard||||55.1%|
+|1665|Minimum Initial Energy to Finish Tasks|[Go]({{< relref "/ChapterFour/1600~1699/1665.Minimum-Initial-Energy-to-Finish-Tasks.md" >}})|Hard||||55.0%|
 |1679|Max Number of K-Sum Pairs|[Go]({{< relref "/ChapterFour/1600~1699/1679.Max-Number-of-K-Sum-Pairs.md" >}})|Medium||||53.5%|
-|1691|Maximum Height by Stacking Cuboids|[Go]({{< relref "/ChapterFour/1600~1699/1691.Maximum-Height-by-Stacking-Cuboids.md" >}})|Hard||||51.1%|
+|1691|Maximum Height by Stacking Cuboids|[Go]({{< relref "/ChapterFour/1600~1699/1691.Maximum-Height-by-Stacking-Cuboids.md" >}})|Hard||||51.2%|
 |1710|Maximum Units on a Truck|[Go]({{< relref "/ChapterFour/1700~1799/1710.Maximum-Units-on-a-Truck.md" >}})|Easy||||72.5%|
 |1818|Minimum Absolute Sum Difference|[Go]({{< relref "/ChapterFour/1800~1899/1818.Minimum-Absolute-Sum-Difference.md" >}})|Medium||||28.4%|
 |1846|Maximum Element After Decreasing and Rearranging|[Go]({{< relref "/ChapterFour/1800~1899/1846.Maximum-Element-After-Decreasing-and-Rearranging.md" >}})|Medium||||55.4%|