algorithm/leetcode-master
1
0
Fork 0
mirror of https://github.com/youngyangyang04/leetcode-master.git synced 2025-07-08 16:54:50 +08:00
Code Issues Packages Projects Releases Wiki Activity

Update 0106.从中序与后序遍历序列构造二叉树.md

Browse Source 
优化js版本代码并添加注释说明
This commit is contained in:
Junwen Huang
2021-10-23 20:47:43 +08:00
committed by GitHub
parent 3d303eb135
commit 74cb27fa2c
1 changed files with 14 additions and 17 deletions
Download Patch File Download Diff File Expand all files Collapse all files

29
problems/0106.从中序与后序遍历序列构造二叉树.md
View File

@ -792,16 +792,13 @@ func findRootIndex(target int,inorder []int) int{
```javascript
var buildTree = function(inorder, postorder) {
if (!postorder.length) return null
let root = new TreeNode(postorder[postorder.length - 1])
let index = inorder.findIndex(number => number === root.val)
root.left = buildTree(inorder.slice(0, index), postorder.slice(0, index))
root.right = buildTree(inorder.slice(index + 1, inorder.length), postorder.slice(index, postorder.length - 1))
return root
if (!preorder.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
root.left = buildTree(inorder.slice(0, rootIndex), postorder.slice(0, rootIndex)); // 创建左节点
root.right = buildTree(inorder.slice(rootIndex + 1), postorder.slice(rootIndex)); // 创建右节点
return root;
};
```
@ -809,12 +806,12 @@ var buildTree = function(inorder, postorder) {
```javascript
var buildTree = function(preorder, inorder) {
if(!preorder.length)
return null;
let root = new TreeNode(preorder[0]);
let mid = inorder.findIndex((number) => number === root.val);
root.left = buildTree(preorder.slice(1, mid + 1), inorder.slice(0, mid));
root.right = buildTree(preorder.slice(mid + 1, preorder.length), inorder.slice(mid + 1, inorder.length));
if (!preorder.length) return null;
const rootVal = preorder.shift(); // 从前序遍历的数组中获取中间节点的值， 即数组第一个值
const index = 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
root.left = buildTree(preorder.slice(0, index), inorder.slice(0, index)); // 创建左节点
root.right = buildTree(preorder.slice(index), inorder.slice(index + 1)); // 创建右节点
return root;
};
```