Merge branch 'youngyangyang04:master' into master

problems/0222.完全二叉树的节点个数.md

@@ -335,6 +335,30 @@ func countNodes(root *TreeNode) int {
 }
 ```
 
+利用完全二叉树特性的递归解法
+```go
+func countNodes(root *TreeNode) int {
+    if root == nil {
+        return 0
+    }
+    leftH, rightH := 0, 0
+    leftNode := root.Left
+    rightNode := root.Right
+    for leftNode != nil {
+        leftNode = leftNode.Left
+        leftH++
+    }
+    for rightNode != nil {
+        rightNode = rightNode.Right
+        rightH++
+    }
+    if leftH == rightH {
+        return (2 << leftH) - 1
+    }
+    return countNodes(root.Left) + countNodes(root.Right) + 1
+}
+```
+
 
 
 JavaScript:

problems/0257.二叉树的所有路径.md

@@ -351,6 +351,29 @@ class Solution:
 ```
 Go：
   
+```go
+func binaryTreePaths(root *TreeNode) []string {
+    res := make([]string, 0)
+    var travel func(node *TreeNode, s string)
+    travel = func(node *TreeNode, s string) {
+        if node.Left == nil && node.Right == nil {
+            v := s + strconv.Itoa(node.Val)
+            res = append(res, v)
+            return
+        }
+        s = s + strconv.Itoa(node.Val) + "->"
+        if node.Left != nil {
+            travel(node.Left, s)
+        }
+        if node.Right != nil {
+            travel(node.Right, s)
+        }
+    }
+    travel(root, "")
+    return res
+}
+```
+
 JavaScript:
 1.递归版本
 ```javascript