Merge pull request #1491 from jujunwang/master

添加（1382. 将二叉搜索树变平衡    0031.下一个排列）的go版本

problems/0031.下一个排列.md

@@ -171,13 +171,13 @@ class Solution(object):
         i = n-2
         while i >= 0 and nums[i] >= nums[i+1]:
             i -= 1
-        
+
         if i > -1: // i==-1,不存在下一个更大的排列
             j = n-1
             while j >= 0 and nums[j] <= nums[i]:
                 j -= 1
             nums[i], nums[j] = nums[j], nums[i]
-
+    
         start, end = i+1, n-1
         while start < end:
             nums[start], nums[end] = nums[end], nums[start]
@@ -190,6 +190,26 @@ class Solution(object):
 ## Go
 
 ```go
+//卡尔的解法
+func nextPermutation(nums []int)  {
+    for i:=len(nums)-1;i>=0;i--{
+        for j:=len(nums)-1;j>i;j--{
+            if nums[j]>nums[i]{
+                //交换
+                nums[j],nums[i]=nums[i],nums[j]
+                reverse(nums,0+i+1,len(nums)-1)
+                return 
+            }
+        }
+    }
+    reverse(nums,0,len(nums)-1)
+}
+//对目标切片指定区间的反转方法
+func reverse(a []int,begin,end int){
+    for i,j:=begin,end;i<j;i,j=i+1,j-1{
+        a[i],a[j]=a[j],a[i]
+    }
+}
 ```
 
 ## JavaScript

problems/1382.将二叉搜索树变平衡.md

@@ -123,6 +123,46 @@ class Solution:
 ```
 Go：
 
+```go
+/**
+ * Definition for a binary tree node.
+ * type TreeNode struct {
+ *     Val int
+ *     Left *TreeNode
+ *     Right *TreeNode
+ * }
+ */
+func balanceBST(root *TreeNode) *TreeNode {
+   // 二叉搜索树中序遍历得到有序数组
+	nums := []int{}
+   // 中序递归遍历二叉树
+	var travel func(node *TreeNode)
+	travel = func(node *TreeNode) {
+		if node == nil {
+			return
+		}
+		travel(node.Left)
+		nums = append(nums, node.Val)
+		travel(node.Right)
+	}
+	// 二分法保证左右子树高度差不超过一（题目要求返回的仍是二叉搜索树）
+	var buildTree func(nums []int, left, right int) *TreeNode
+	buildTree = func(nums []int, left, right int) *TreeNode {
+		if left > right {
+			return nil
+		}
+		mid := left + (right-left) >> 1
+		root := &TreeNode{Val: nums[mid]}
+		root.Left = buildTree(nums, left, mid-1)
+		root.Right = buildTree(nums, mid+1, right)
+		return root
+	}
+	travel(root)
+	return buildTree(nums, 0, len(nums)-1)
+}
+
+```
+
 JavaScript：
 ```javascript
 var balanceBST = function(root) {