添加二叉树：以为使用了递归，其实还隐藏着回溯 go版本

andyliao5555 · Jun 12, 2021 · ecf5ff1 · ecf5ff1
1 parent 2c24d81
commit ecf5ff1
Showing 1 changed file with 104 additions and 0 deletions.
diff --git a/problems/二叉树中递归带着回溯.md b/problems/二叉树中递归带着回溯.md
@@ -336,6 +336,110 @@ class Solution:
 ```
 
 Go：
+100.相同的树
+```go
+/**
+ * Definition for a binary tree node.
+ * type TreeNode struct {
+ *     Val int
+ *     Left *TreeNode
+ *     Right *TreeNode
+ * }
+ */
+func isSameTree(p *TreeNode, q *TreeNode) bool {
+   	switch {
+	case p == nil && q == nil:
+		return true
+	case p == nil || q == nil:
+    fmt.Println(p,q)
+		fallthrough
+	case p.Val != q.Val:
+		return false
+	}
+	return isSameTree(p.Left, q.Left) && isSameTree(p.Right, q.Right)
+}
+```
+
+257.二叉的所有路径
+> 递归法
+
+```go
+/**
+ * Definition for a binary tree node.
+ * type TreeNode struct {
+ *     Val int
+ *     Left *TreeNode
+ *     Right *TreeNode
+ * }
+ */
+func binaryTreePaths(root *TreeNode) []string {
+    var result []string
+    traversal(root,&result,"")
+    return result
+}
+func traversal(root *TreeNode,result *[]string,pathStr string){
+    //判断是否为第一个元素
+    if len(pathStr)!=0{
+        pathStr=pathStr+"->"+strconv.Itoa(root.Val)
+    }else{
+        pathStr=strconv.Itoa(root.Val)
+    }
+    //判断是否为叶子节点
+    if root.Left==nil&&root.Right==nil{
+        *result=append(*result,pathStr)
+        return 
+    }
+    //左右
+    if root.Left!=nil{
+        traversal(root.Left,result,pathStr)
+    }
+    if root.Right!=nil{
+        traversal(root.Right,result,pathStr)
+    }
+}
+```
+
+> 回溯法
+
+```go
+/**
+ * Definition for a binary tree node.
+ * type TreeNode struct {
+ *     Val int
+ *     Left *TreeNode
+ *     Right *TreeNode
+ * }
+ */
+func binaryTreePaths(root *TreeNode) []string {
+    var result []string
+    var path   []int
+    traversal(root,&result,&path)
+    return result
+}
+func traversal(root *TreeNode,result *[]string,path *[]int){
+    *path=append(*path,root.Val)
+    //判断是否为叶子节点
+    if root.Left==nil&&root.Right==nil{
+        pathStr:=strconv.Itoa((*path)[0])
+        for i:=1;i<len(*path);i++{
+            pathStr=pathStr+"->"+strconv.Itoa((*path)[i])
+        }
+        *result=append(*result,pathStr)
+        return 
+    }
+    //左右
+    if root.Left!=nil{
+        traversal(root.Left,result,path)
+        *path=(*path)[:len(*path)-1]//回溯到上一个节点（因为traversal会加下一个节点值到path中）
+    }
+    if root.Right!=nil{
+        traversal(root.Right,result,path)
+        *path=(*path)[:len(*path)-1]//回溯
+    }
+}
+```
+
+