Merge branch 'master' into remote

problems/0226.翻转二叉树.md

@@ -363,7 +363,9 @@ class Solution:
         return root
 ```
 
-### Go 
+### Go
+
+递归版本的前序遍历
 
 ```Go
 func invertTree(root *TreeNode) *TreeNode {
@@ -381,6 +383,96 @@ func invertTree(root *TreeNode) *TreeNode {
 }
 ```
 
+递归版本的后序遍历
+
+```go
+func invertTree(root *TreeNode) *TreeNode {
+    if root==nil{
+        return root
+    }
+    invertTree(root.Left)//遍历左节点
+    invertTree(root.Right)//遍历右节点
+    root.Left,root.Right=root.Right,root.Left//交换
+    return root
+}
+```
+
+迭代版本的前序遍历
+
+```go
+func invertTree(root *TreeNode) *TreeNode {
+    stack:=[]*TreeNode{}
+    node:=root
+    for node!=nil||len(stack)>0{
+        for node!=nil{
+            node.Left,node.Right=node.Right,node.Left//交换
+            stack=append(stack,node)
+            node=node.Left
+        }
+        node=stack[len(stack)-1]
+        stack=stack[:len(stack)-1]
+        node=node.Right
+    }
+    return root
+}
+```
+
+迭代版本的后序遍历
+
+```go
+func invertTree(root *TreeNode) *TreeNode {
+    stack:=[]*TreeNode{}
+    node:=root
+    var prev *TreeNode
+    for node!=nil||len(stack)>0{
+        for node!=nil{
+            stack=append(stack,node)
+            node=node.Left
+        }
+        node=stack[len(stack)-1]
+        stack=stack[:len(stack)-1]
+        if node.Right==nil||node.Right==prev{
+            node.Left,node.Right=node.Right,node.Left//交换
+            prev=node
+            node=nil
+        }else {
+            stack=append(stack,node)
+            node=node.Right
+        }
+    }
+    return root
+}
+```
+
+层序遍历
+
+```go
+func invertTree(root *TreeNode) *TreeNode {
+    if root==nil{
+        return root
+    }
+    queue:=list.New()
+    node:=root
+    queue.PushBack(node)
+    for queue.Len()>0{
+        length:=queue.Len()
+        for i:=0;i<length;i++{
+            e:=queue.Remove(queue.Front()).(*TreeNode)
+            e.Left,e.Right=e.Right,e.Left//交换
+            if e.Left!=nil{
+                queue.PushBack(e.Left)
+            }
+            if e.Right!=nil{
+                queue.PushBack(e.Right)
+            }
+        }
+    }
+    return root
+}
+```
+
+
+
 ### JavaScript
 
 使用递归版本的前序遍历
@@ -522,4 +614,4 @@ struct TreeNode* invertTree(struct TreeNode* root){
 * 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)
-<div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码.jpg width=450> </img></div>
+<div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>