Merge pull request youngyangyang04#1197 from Merry9/master

修改二叉树系列19 从中序与后序遍历序列构造二叉树JS版本变量名 preorder->inorder

Author: youngyangyang04

problems/0106.从中序与后序遍历序列构造二叉树.md

@@ -790,7 +790,7 @@ func findRootIndex(target int,inorder []int) int{
 
 ```javascript
 var buildTree = function(inorder, postorder) {
-    if (!preorder.length) return null;
+    if (!inorder.length) return null;
     const rootVal = postorder.pop(); // 从后序遍历的数组中获取中间节点的值， 即数组最后一个值
     let rootIndex = inorder.indexOf(rootVal); // 获取中间节点在中序遍历中的下标
     const root = new TreeNode(rootVal); // 创建中间节点

problems/0108.将有序数组转换为二叉搜索树.md

@@ -355,6 +355,7 @@ func sortedArrayToBST(nums []int) *TreeNode {
 ```
 
 ## JavaScript 
+递归
 
 ```javascript
 var sortedArrayToBST = function (nums) {
@@ -372,7 +373,44 @@ var sortedArrayToBST = function (nums) {
     return buildTree(nums, 0, nums.length - 1);
 };
 ```
-
+迭代
+```JavaScript
+var sortedArrayToBST = function(nums) {
+    if(nums.length===0){
+        return null;
+    }
+    let root=new TreeNode(0); //初始根节点
+    let nodeQue=[root]; //放遍历的节点,并初始化
+    let leftQue=[0]; //放左区间的下标,初始化
+    let rightQue=[nums.length-1]; // 放右区间的下标
+    
+    while(nodeQue.length){
+        let curNode=nodeQue.pop();
+        let left=leftQue.pop();
+        let right=rightQue.pop();
+        let mid=left+Math.floor((right-left)/2);
+        
+        curNode.val=nums[mid]; //将下标为mid的元素给中间节点
+        
+//         处理左区间
+        if(left<=mid-1){
+            curNode.left=new TreeNode(0);
+            nodeQue.push(curNode.left);
+            leftQue.push(left);
+            rightQue.push(mid-1);
+        }
+        
+//         处理右区间
+        if(right>=mid+1){
+            curNode.right=new TreeNode(0);
+            nodeQue.push(curNode.right);
+            leftQue.push(mid+1);
+            rightQue.push(right);
+        }
+    }
+    return root;
+};
+```
 ## TypeScript
 
 ```typescript