diff --git a/problems/0001.两数之和.md b/problems/0001.两数之和.md
index 41a95daf..02e9996f 100644
--- a/problems/0001.两数之和.md
+++ b/problems/0001.两数之和.md
@@ -135,6 +135,21 @@ func twoSum(nums []int, target int) []int {
}
```
+```go
+// 使用map方式解题,降低时间复杂度
+func twoSum(nums []int, target int) []int {
+ m := make(map[int]int)
+ for index, val := range nums {
+ if preIndex, ok := m[target-val]; ok {
+ return []int{preIndex, index}
+ } else {
+ m[val] = index
+ }
+ }
+ return []int{}
+}
+```
+
Rust
```rust
diff --git a/problems/0028.实现strStr.md b/problems/0028.实现strStr.md
index 6f257d5e..04508440 100644
--- a/problems/0028.实现strStr.md
+++ b/problems/0028.实现strStr.md
@@ -721,10 +721,98 @@ class Solution:
Go:
+```go
+// 方法一:前缀表使用减1实现
+
+// getNext 构造前缀表next
+// params:
+// next 前缀表数组
+// s 模式串
+func getNext(next []int, s string) {
+ j := -1 // j表示 最长相等前后缀长度
+ next[0] = j
+
+ for i := 1; i < len(s); i++ {
+ for j >= 0 && s[i] != s[j+1] {
+ j = next[j] // 回退前一位
+ }
+ if s[i] == s[j+1] {
+ j++
+ }
+ next[i] = j // next[i]是i(包括i)之前的最长相等前后缀长度
+ }
+}
+func strStr(haystack string, needle string) int {
+ if len(needle) == 0 {
+ return 0
+ }
+ next := make([]int, len(needle))
+ getNext(next, needle)
+ j := -1 // 模式串的起始位置 next为-1 因此也为-1
+ for i := 0; i < len(haystack); i++ {
+ for j >= 0 && haystack[i] != needle[j+1] {
+ j = next[j] // 寻找下一个匹配点
+ }
+ if haystack[i] == needle[j+1] {
+ j++
+ }
+ if j == len(needle)-1 { // j指向了模式串的末尾
+ return i - len(needle) + 1
+ }
+ }
+ return -1
+}
+```
+
+```go
+// 方法二: 前缀表无减一或者右移
+
+// getNext 构造前缀表next
+// params:
+// next 前缀表数组
+// s 模式串
+func getNext(next []int, s string) {
+ j := 0
+ next[0] = j
+ for i := 1; i < len(s); i++ {
+ for j > 0 && s[i] != s[j] {
+ j = next[j-1]
+ }
+ if s[i] == s[j] {
+ j++
+ }
+ next[i] = j
+ }
+}
+func strStr(haystack string, needle string) int {
+ n := len(needle)
+ if n == 0 {
+ return 0
+ }
+ j := 0
+ next := make([]int, n)
+ getNext(next, needle)
+ for i := 0; i < len(haystack); i++ {
+ for j > 0 && haystack[i] != needle[j] {
+ j = next[j-1] // 回退到j的前一位
+ }
+ if haystack[i] == needle[j] {
+ j++
+ }
+ if j == n {
+ return i - n + 1
+ }
+ }
+ return -1
+}
+```
+
+
+
-----------------------
* 作者微信:[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw)
* B站视频:[代码随想录](https://space.bilibili.com/525438321)
* 知识星球:[代码随想录](https://mp.weixin.qq.com/s/QVF6upVMSbgvZy8lHZS3CQ)
-
+
\ No newline at end of file
diff --git a/problems/0037.解数独.md b/problems/0037.解数独.md
index d5df95e8..4eb60704 100644
--- a/problems/0037.解数独.md
+++ b/problems/0037.解数独.md
@@ -287,7 +287,39 @@ class Solution {
```
Python:
-
+```python3
+class Solution:
+ def solveSudoku(self, board: List[List[str]]) -> None:
+ """
+ Do not return anything, modify board in-place instead.
+ """
+ def backtrack(board):
+ for i in range(len(board)): #遍历行
+ for j in range(len(board[0])): #遍历列
+ if board[i][j] != ".": continue
+ for k in range(1,10): #(i, j) 这个位置放k是否合适
+ if isValid(i,j,k,board):
+ board[i][j] = str(k) #放置k
+ if backtrack(board): return True #如果找到合适一组立刻返回
+ board[i][j] = "." #回溯,撤销k
+ return False #9个数都试完了,都不行,那么就返回false
+ return True #遍历完没有返回false,说明找到了合适棋盘位置了
+ def isValid(row,col,val,board):
+ for i in range(9): #判断行里是否重复
+ if board[row][i] == str(val):
+ return False
+ for j in range(9): #判断列里是否重复
+ if board[j][col] == str(val):
+ return False
+ startRow = (row // 3) * 3
+ startcol = (col // 3) * 3
+ for i in range(startRow,startRow + 3): #判断9方格里是否重复
+ for j in range(startcol,startcol + 3):
+ if board[i][j] == str(val):
+ return False
+ return True
+ backtrack(board)
+```
Go:
diff --git a/problems/0056.合并区间.md b/problems/0056.合并区间.md
index eb8e7bff..d4ffc554 100644
--- a/problems/0056.合并区间.md
+++ b/problems/0056.合并区间.md
@@ -141,16 +141,7 @@ Java:
class Solution {
public int[][] merge(int[][] intervals) {
List res = new LinkedList<>();
- Arrays.sort(intervals, new Comparator() {
- @Override
- public int compare(int[] o1, int[] o2) {
- if (o1[0] != o2[0]) {
- return Integer.compare(o1[0],o2[0]);
- } else {
- return Integer.compare(o1[1],o2[1]);
- }
- }
- });
+ Arrays.sort(intervals, (o1, o2) -> Integer.compare(o1[0], o2[0]));
int start = intervals[0][0];
for (int i = 1; i < intervals.length; i++) {
diff --git a/problems/0101.对称二叉树.md b/problems/0101.对称二叉树.md
index d8797d30..b58cef2e 100644
--- a/problems/0101.对称二叉树.md
+++ b/problems/0101.对称二叉树.md
@@ -363,6 +363,54 @@ Python:
Go:
+```go
+/**
+ * Definition for a binary tree node.
+ * type TreeNode struct {
+ * Val int
+ * Left *TreeNode
+ * Right *TreeNode
+ * }
+ */
+// 递归
+func defs(left *TreeNode, right *TreeNode) bool {
+ if left == nil && right == nil {
+ return true;
+ };
+ if left == nil || right == nil {
+ return false;
+ };
+ if left.Val != right.Val {
+ return false;
+ }
+ return defs(left.Left, right.Right) && defs(right.Left, left.Right);
+}
+func isSymmetric(root *TreeNode) bool {
+ return defs(root.Left, root.Right);
+}
+
+// 迭代
+func isSymmetric(root *TreeNode) bool {
+ var queue []*TreeNode;
+ if root != nil {
+ queue = append(queue, root.Left, root.Right);
+ }
+ for len(queue) > 0 {
+ left := queue[0];
+ right := queue[1];
+ queue = queue[2:];
+ if left == nil && right == nil {
+ continue;
+ }
+ if left == nil || right == nil || left.Val != right.Val {
+ return false;
+ };
+ queue = append(queue, left.Left, right.Right, right.Left, left.Right);
+ }
+ return true;
+}
+```
+
JavaScript
```javascript
diff --git a/problems/0104.二叉树的最大深度.md b/problems/0104.二叉树的最大深度.md
index 756afb68..5f0fe411 100644
--- a/problems/0104.二叉树的最大深度.md
+++ b/problems/0104.二叉树的最大深度.md
@@ -284,6 +284,55 @@ Python:
Go:
+```go
+/**
+ * Definition for a binary tree node.
+ * type TreeNode struct {
+ * Val int
+ * Left *TreeNode
+ * Right *TreeNode
+ * }
+ */
+func max (a, b int) int {
+ if a > b {
+ return a;
+ }
+ return b;
+}
+// 递归
+func maxDepth(root *TreeNode) int {
+ if root == nil {
+ return 0;
+ }
+ return max(maxDepth(root.Left), maxDepth(root.Right)) + 1;
+}
+
+// 遍历
+func maxDepth(root *TreeNode) int {
+ levl := 0;
+ queue := make([]*TreeNode, 0);
+ if root != nil {
+ queue = append(queue, root);
+ }
+ for l := len(queue); l > 0; {
+ for ;l > 0;l-- {
+ node := queue[0];
+ if node.Left != nil {
+ queue = append(queue, node.Left);
+ }
+ if node.Right != nil {
+ queue = append(queue, node.Right);
+ }
+ queue = queue[1:];
+ }
+ levl++;
+ l = len(queue);
+ }
+ return levl;
+}
+
+```
+
JavaScript
```javascript
diff --git a/problems/0111.二叉树的最小深度.md b/problems/0111.二叉树的最小深度.md
index 8ee15eac..48795722 100644
--- a/problems/0111.二叉树的最小深度.md
+++ b/problems/0111.二叉树的最小深度.md
@@ -301,6 +301,64 @@ class Solution:
Go:
+```go
+/**
+ * Definition for a binary tree node.
+ * type TreeNode struct {
+ * Val int
+ * Left *TreeNode
+ * Right *TreeNode
+ * }
+ */
+func min(a, b int) int {
+ if a < b {
+ return a;
+ }
+ return b;
+}
+// 递归
+func minDepth(root *TreeNode) int {
+ if root == nil {
+ return 0;
+ }
+ if root.Left == nil && root.Right != nil {
+ return 1 + minDepth(root.Right);
+ }
+ if root.Right == nil && root.Left != nil {
+ return 1 + minDepth(root.Left);
+ }
+ return min(minDepth(root.Left), minDepth(root.Right)) + 1;
+}
+
+// 迭代
+
+func minDepth(root *TreeNode) int {
+ dep := 0;
+ queue := make([]*TreeNode, 0);
+ if root != nil {
+ queue = append(queue, root);
+ }
+ for l := len(queue); l > 0; {
+ dep++;
+ for ; l > 0; l-- {
+ node := queue[0];
+ if node.Left == nil && node.Right == nil {
+ return dep;
+ }
+ if node.Left != nil {
+ queue = append(queue, node.Left);
+ }
+ if node.Right != nil {
+ queue = append(queue, node.Right);
+ }
+ queue = queue[1:];
+ }
+ l = len(queue);
+ }
+ return dep;
+}
+```
+
JavaScript:
diff --git a/problems/0112.路径总和.md b/problems/0112.路径总和.md
index 4ccd8912..d810a046 100644
--- a/problems/0112.路径总和.md
+++ b/problems/0112.路径总和.md
@@ -345,6 +345,36 @@ class Solution {
return hasPathSum(root.left, targetSum - root.val) || hasPathSum(root.right, targetSum - root.val);
}
}
+```
+迭代
+```java
+class Solution {
+ public boolean hasPathSum(TreeNode root, int targetSum) {
+ if(root==null)return false;
+ Stack stack1 = new Stack<>();
+ Stack stack2 = new Stack<>();
+ stack1.push(root);stack2.push(root.val);
+ while(!stack1.isEmpty()){
+ int size = stack1.size();
+ for(int i=0;i ratings[i - 1]) {
+ candys[i] = candys[i - 1] + 1
+ }
+ }
+
+ for(let i = ratings.length - 2; i >= 0; i--) {
+ if(ratings[i] > ratings[i + 1]) {
+ candys[i] = Math.max(candys[i], candys[i + 1] + 1)
+ }
+ }
+
+ let count = candys.reduce((a, b) => {
+ return a + b
+ })
+
+ return count
+};
+```
-----------------------
diff --git a/problems/0151.翻转字符串里的单词.md b/problems/0151.翻转字符串里的单词.md
index 512360fe..63499b71 100644
--- a/problems/0151.翻转字符串里的单词.md
+++ b/problems/0151.翻转字符串里的单词.md
@@ -318,9 +318,61 @@ class Solution {
Python:
-
Go:
+```go
+import (
+ "fmt"
+)
+
+func reverseWords(s string) string {
+ //1.使用双指针删除冗余的空格
+ slowIndex, fastIndex := 0, 0
+ b := []byte(s)
+ //删除头部冗余空格
+ for len(b) > 0 && fastIndex < len(b) && b[fastIndex] == ' ' {
+ fastIndex++
+ }
+ //删除单词间冗余空格
+ for ; fastIndex < len(b); fastIndex++ {
+ if fastIndex-1 > 0 && b[fastIndex-1] == b[fastIndex] && b[fastIndex] == ' ' {
+ continue
+ }
+ b[slowIndex] = b[fastIndex]
+ slowIndex++
+ }
+ //删除尾部冗余空格
+ if slowIndex-1 > 0 && b[slowIndex-1] == ' ' {
+ b = b[:slowIndex-1]
+ } else {
+ b = b[:slowIndex]
+ }
+ //2.反转整个字符串
+ reverse(&b, 0, len(b)-1)
+ //3.反转单个单词 i单词开始位置,j单词结束位置
+ i := 0
+ for i < len(b) {
+ j := i
+ for ; j < len(b) && b[j] != ' '; j++ {
+ }
+ reverse(&b, i, j-1)
+ i = j
+ i++
+ }
+ return string(b)
+}
+
+func reverse(b *[]byte, left, right int) {
+ for left < right {
+ (*b)[left], (*b)[right] = (*b)[right], (*b)[left]
+ left++
+ right--
+ }
+}
+```
+
+
+
@@ -328,4 +380,4 @@ Go:
* 作者微信:[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw)
* B站视频:[代码随想录](https://space.bilibili.com/525438321)
* 知识星球:[代码随想录](https://mp.weixin.qq.com/s/QVF6upVMSbgvZy8lHZS3CQ)
-
+
\ No newline at end of file
diff --git a/problems/0239.滑动窗口最大值.md b/problems/0239.滑动窗口最大值.md
index ed17157a..47383a47 100644
--- a/problems/0239.滑动窗口最大值.md
+++ b/problems/0239.滑动窗口最大值.md
@@ -263,6 +263,41 @@ class Solution {
```
Python:
+```python
+class MyQueue: #单调队列(从大到小
+ def __init__(self):
+ self.queue = [] #使用list来实现单调队列
+
+ #每次弹出的时候,比较当前要弹出的数值是否等于队列出口元素的数值,如果相等则弹出。
+ #同时pop之前判断队列当前是否为空。
+ def pop(self, value):
+ if self.queue and value == self.queue[0]:
+ self.queue.pop(0)#list.pop()时间复杂度为O(n),这里可以使用collections.deque()
+
+ #如果push的数值大于入口元素的数值,那么就将队列后端的数值弹出,直到push的数值小于等于队列入口元素的数值为止。
+ #这样就保持了队列里的数值是单调从大到小的了。
+ def push(self, value):
+ while self.queue and value > self.queue[-1]:
+ self.queue.pop()
+ self.queue.append(value)
+
+ #查询当前队列里的最大值 直接返回队列前端也就是front就可以了。
+ def front(self):
+ return self.queue[0]
+
+class Solution:
+ def maxSlidingWindow(self, nums: List[int], k: int) -> List[int]:
+ que = MyQueue()
+ result = []
+ for i in range(k): #先将前k的元素放进队列
+ que.push(nums[i])
+ result.append(que.front()) #result 记录前k的元素的最大值
+ for i in range(k, len(nums)):
+ que.pop(nums[i - k]) #滑动窗口移除最前面元素
+ que.push(nums[i]) #滑动窗口前加入最后面的元素
+ result.append(que.front()) #记录对应的最大值
+ return result
+```
Go:
diff --git a/problems/0347.前K个高频元素.md b/problems/0347.前K个高频元素.md
index 841584b4..71af618e 100644
--- a/problems/0347.前K个高频元素.md
+++ b/problems/0347.前K个高频元素.md
@@ -162,7 +162,33 @@ class Solution {
Python:
-
+```python
+#时间复杂度:O(nlogk)
+#空间复杂度:O(n)
+import heapq
+class Solution:
+ def topKFrequent(self, nums: List[int], k: int) -> List[int]:
+ #要统计元素出现频率
+ map_ = {} #nums[i]:对应出现的次数
+ for i in range(len(nums)):
+ map_[nums[i]] = map_.get(nums[i], 0) + 1
+
+ #对频率排序
+ #定义一个小顶堆,大小为k
+ pri_que = [] #小顶堆
+
+ #用固定大小为k的小顶堆,扫面所有频率的数值
+ for key, freq in map_.items():
+ heapq.heappush(pri_que, (freq, key))
+ if len(pri_que) > k: #如果堆的大小大于了K,则队列弹出,保证堆的大小一直为k
+ heapq.heappop(pri_que)
+
+ #找出前K个高频元素,因为小顶堆先弹出的是最小的,所以倒叙来输出到数组
+ result = [0] * k
+ for i in range(k-1, -1, -1):
+ result[i] = heapq.heappop(pri_que)[1]
+ return result
+```
Go:
diff --git a/problems/0376.摆动序列.md b/problems/0376.摆动序列.md
index 6fa30cde..bbca5ea0 100644
--- a/problems/0376.摆动序列.md
+++ b/problems/0376.摆动序列.md
@@ -138,7 +138,21 @@ class Solution {
```
Python:
-
+```python
+class Solution:
+ def wiggleMaxLength(self, nums: List[int]) -> int:
+ #贪心 求波峰数量 + 波谷数量
+ if len(nums)<=1:
+ return len(nums)
+ cur, pre = 0,0 #当前一对差值,前一对差值
+ count = 1#默认最右边有一个峰值
+ for i in range(len(nums)-1):
+ cur = nums[i+1] - nums[i]
+ if((cur>0 and pre<=0) or (cur<0 and pre>=0)):
+ count += 1
+ pre = cur
+ return count
+```
Go:
diff --git a/problems/0383.赎金信.md b/problems/0383.赎金信.md
index fd8175db..23e2c5fd 100644
--- a/problems/0383.赎金信.md
+++ b/problems/0383.赎金信.md
@@ -166,6 +166,21 @@ class Solution(object):
```
Go:
+```go
+func canConstruct(ransomNote string, magazine string) bool {
+ record := make([]int, 26)
+ for _, v := range magazine {
+ record[v-'a']++
+ }
+ for _, v := range ransomNote {
+ record[v-'a']--
+ if record[v-'a'] < 0 {
+ return false
+ }
+ }
+ return true
+}
+```
javaScript:
diff --git a/problems/0454.四数相加II.md b/problems/0454.四数相加II.md
index 939ed20d..835178dd 100644
--- a/problems/0454.四数相加II.md
+++ b/problems/0454.四数相加II.md
@@ -153,6 +153,23 @@ class Solution(object):
Go:
+```go
+func fourSumCount(nums1 []int, nums2 []int, nums3 []int, nums4 []int) int {
+ m := make(map[int]int)
+ count := 0
+ for _, v1 := range nums1 {
+ for _, v2 := range nums2 {
+ m[v1+v2]++
+ }
+ }
+ for _, v3 := range nums3 {
+ for _, v4 := range nums4 {
+ count += m[-v3-v4]
+ }
+ }
+ return count
+}
+```
javaScript:
diff --git a/problems/0455.分发饼干.md b/problems/0455.分发饼干.md
index b3714c43..ecf7f132 100644
--- a/problems/0455.分发饼干.md
+++ b/problems/0455.分发饼干.md
@@ -134,7 +134,21 @@ class Solution {
```
Python:
-
+```python
+class Solution:
+ def findContentChildren(self, g: List[int], s: List[int]) -> int:
+ #先考虑胃口小的孩子
+ g.sort()
+ s.sort()
+ i=j=0
+ count = 0
+ while(i bool:
+ if len(s) == 0:
+ return False
+ nxt = [0] * len(s)
+ self.getNext(nxt, s)
+ if nxt[-1] != -1 and len(s) % (len(s) - (nxt[-1] + 1)) == 0:
+ return True
+ return False
+
+ def getNext(self, nxt, s):
+ nxt[0] = -1
+ j = -1
+ for i in range(1, len(s)):
+ while j >= 0 and s[i] != s[j+1]:
+ j = nxt[j]
+ if s[i] == s[j+1]:
+ j += 1
+ nxt[i] = j
+ return nxt
+```
+
+前缀表(不减一)的代码实现
+
+```python
+class Solution:
+ def repeatedSubstringPattern(self, s: str) -> bool:
+ if len(s) == 0:
+ return False
+ nxt = [0] * len(s)
+ self.getNext(nxt, s)
+ if nxt[-1] != 0 and len(s) % (len(s) - nxt[-1]) == 0:
+ return True
+ return False
+
+ def getNext(self, nxt, s):
+ nxt[0] = 0
+ j = 0
+ for i in range(1, len(s)):
+ while j > 0 and s[i] != s[j]:
+ j = nxt[j - 1]
+ if s[i] == s[j]:
+ j += 1
+ nxt[i] = j
+ return nxt
+```
Go:
+这里使用了前缀表统一减一的实现方式
+
+```go
+func repeatedSubstringPattern(s string) bool {
+ n := len(s)
+ if n == 0 {
+ return false
+ }
+ next := make([]int, n)
+ j := -1
+ next[0] = j
+ for i := 1; i < n; i++ {
+ for j >= 0 && s[i] != s[j+1] {
+ j = next[j]
+ }
+ if s[i] == s[j+1] {
+ j++
+ }
+ next[i] = j
+ }
+ // next[n-1]+1 最长相同前后缀的长度
+ if next[n-1] != -1 && n%(n-(next[n-1]+1)) == 0 {
+ return true
+ }
+ return false
+}
+```
+
+前缀表(不减一)的代码实现
+
+```go
+func repeatedSubstringPattern(s string) bool {
+ n := len(s)
+ if n == 0 {
+ return false
+ }
+ j := 0
+ next := make([]int, n)
+ next[0] = j
+ for i := 1; i < n; i++ {
+ for j > 0 && s[i] != s[j] {
+ j = next[j-1]
+ }
+ if s[i] == s[j] {
+ j++
+ }
+ next[i] = j
+ }
+ // next[n-1] 最长相同前后缀的长度
+ if next[n-1] != 0 && n%(n-next[n-1]) == 0 {
+ return true
+ }
+ return false
+}
+```
+
+
+
@@ -194,4 +301,4 @@ Go:
* 作者微信:[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw)
* B站视频:[代码随想录](https://space.bilibili.com/525438321)
* 知识星球:[代码随想录](https://mp.weixin.qq.com/s/QVF6upVMSbgvZy8lHZS3CQ)
-
+
\ No newline at end of file
diff --git a/problems/0494.目标和.md b/problems/0494.目标和.md
index c772a09d..c917ed5c 100644
--- a/problems/0494.目标和.md
+++ b/problems/0494.目标和.md
@@ -276,7 +276,35 @@ class Solution:
```
Go:
-
+```go
+func findTargetSumWays(nums []int, target int) int {
+ sum := 0
+ for _, v := range nums {
+ sum += v
+ }
+ if target > sum {
+ return 0
+ }
+ if (sum+target)%2 == 1 {
+ return 0
+ }
+ // 计算背包大小
+ bag := (sum + target) / 2
+ // 定义dp数组
+ dp := make([]int, bag+1)
+ // 初始化
+ dp[0] = 1
+ // 遍历顺序
+ for i := 0; i < len(nums); i++ {
+ for j := bag; j >= nums[i]; j-- {
+ //推导公式
+ dp[j] += dp[j-nums[i]]
+ //fmt.Println(dp)
+ }
+ }
+ return dp[bag]
+}
+```
diff --git a/problems/1049.最后一块石头的重量II.md b/problems/1049.最后一块石头的重量II.md
index f74600b1..c09e476a 100644
--- a/problems/1049.最后一块石头的重量II.md
+++ b/problems/1049.最后一块石头的重量II.md
@@ -191,7 +191,33 @@ class Solution:
```
Go:
+```go
+func lastStoneWeightII(stones []int) int {
+ // 15001 = 30 * 1000 /2 +1
+ dp := make([]int, 15001)
+ // 求target
+ sum := 0
+ for _, v := range stones {
+ sum += v
+ }
+ target := sum / 2
+ // 遍历顺序
+ for i := 0; i < len(stones); i++ {
+ for j := target; j >= stones[i]; j-- {
+ // 推导公式
+ dp[j] = max(dp[j], dp[j-stones[i]]+stones[i])
+ }
+ }
+ return sum - 2 * dp[target]
+}
+func max(a, b int) int {
+ if a > b {
+ return a
+ }
+ return b
+}
+```
diff --git a/problems/二叉树的统一迭代法.md b/problems/二叉树的统一迭代法.md
index f4091ad5..533bdfe7 100644
--- a/problems/二叉树的统一迭代法.md
+++ b/problems/二叉树的统一迭代法.md
@@ -239,7 +239,78 @@ Java:
```
Python:
+> 迭代法前序遍历
+```python
+class Solution:
+ def preorderTraversal(self, root: TreeNode) -> List[int]:
+ result = []
+ st= []
+ if root:
+ st.append(root)
+ while st:
+ node = st.pop()
+ if node != None:
+ if node.right: #右
+ st.append(node.right)
+ if node.left: #左
+ st.append(node.left)
+ st.append(node) #中
+ st.append(None)
+ else:
+ node = st.pop()
+ result.append(node.val)
+ return result
+```
+
+> 迭代法中序遍历
+```python
+class Solution:
+ def inorderTraversal(self, root: TreeNode) -> List[int]:
+ result = []
+ st = []
+ if root:
+ st.append(root)
+ while st:
+ node = st.pop()
+ if node != None:
+ if node.right: #添加右节点(空节点不入栈)
+ st.append(node.right)
+
+ st.append(node) #添加中节点
+ st.append(None) #中节点访问过,但是还没有处理,加入空节点做为标记。
+
+ if node.left: #添加左节点(空节点不入栈)
+ st.append(node.left)
+ else: #只有遇到空节点的时候,才将下一个节点放进结果集
+ node = st.pop() #重新取出栈中元素
+ result.append(node.val) #加入到结果集
+ return result
+```
+
+> 迭代法后序遍历
+```python
+class Solution:
+ def postorderTraversal(self, root: TreeNode) -> List[int]:
+ result = []
+ st = []
+ if root:
+ st.append(root)
+ while st:
+ node = st.pop()
+ if node != None:
+ st.append(node) #中
+ st.append(None)
+
+ if node.right: #右
+ st.append(node.right)
+ if node.left: #左
+ st.append(node.left)
+ else:
+ node = st.pop()
+ result.append(node.val)
+ return result
+```
Go:
> 前序遍历统一迭代法
diff --git a/problems/剑指Offer58-II.左旋转字符串.md b/problems/剑指Offer58-II.左旋转字符串.md
index 648546c1..39c8382c 100644
--- a/problems/剑指Offer58-II.左旋转字符串.md
+++ b/problems/剑指Offer58-II.左旋转字符串.md
@@ -23,7 +23,7 @@ https://leetcode-cn.com/problems/zuo-xuan-zhuan-zi-fu-chuan-lcof/
示例 2:
输入: s = "lrloseumgh", k = 6
输出: "umghlrlose"
-
+
限制:
1 <= k < s.length <= 10000
@@ -119,9 +119,31 @@ class Solution {
```
Python:
-
Go:
+```go
+func reverseLeftWords(s string, n int) string {
+ b := []byte(s)
+ // 1. 反转前n个字符
+ // 2. 反转第n到end字符
+ // 3. 反转整个字符
+ reverse(b, 0, n-1)
+ reverse(b, n, len(b)-1)
+ reverse(b, 0, len(b)-1)
+ return string(b)
+}
+// 切片是引用传递
+func reverse(b []byte, left, right int){
+ for left < right{
+ b[left], b[right] = b[right],b[left]
+ left++
+ right--
+ }
+}
+```
+
+
+
@@ -129,4 +151,4 @@ Go:
* 作者微信:[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw)
* B站视频:[代码随想录](https://space.bilibili.com/525438321)
* 知识星球:[代码随想录](https://mp.weixin.qq.com/s/QVF6upVMSbgvZy8lHZS3CQ)
-
+
\ No newline at end of file
diff --git a/problems/链表理论基础.md b/problems/链表理论基础.md
index ea3b9098..252247c7 100644
--- a/problems/链表理论基础.md
+++ b/problems/链表理论基础.md
@@ -83,7 +83,7 @@ struct ListNode {
有同学说了,我不定义构造函数行不行,答案是可以的,C++默认生成一个构造函数。
-但是这个构造函数不会初始化任何成员变化,下面我来举两个例子:
+但是这个构造函数不会初始化任何成员变量,下面我来举两个例子:
通过自己定义构造函数初始化节点: