[leetcode-106]Construct Binary Tree from Inorder and Postorder Traversal(java)

问题描述：
Given inorder and postorder traversal of a tree, construct the binary tree.

Note:
You may assume that duplicates do not exist in the tree.

分析：要构造一个生成树，必须要有一个中序遍历，还要有一个前序或者后序遍历（否则找不到左子树和右子树）。这里与先序遍历相同，也是先确定根节点的位置。然后再递归下去。

代码如下：364ms

/** * Definition for a binary tree node. * public class TreeNode { *     int val; *     TreeNode left; *     TreeNode right; *     TreeNode(int x) { val = x; } * } */public class Solution {    public TreeNode buildTree(int[] inorder, int[] postorder) {        int length = inorder.length;        if(length<=0)            return null;        int rootVal = postorder[length-1];        int point;        for(point = 0;point<length;point++){            if(inorder[point] == rootVal)                break;        }        int[] leftInOrder = Arrays.copyOfRange(inorder,0,point);        int[] rightInOrder = Arrays.copyOfRange(inorder,point+1,length);        int[] leftPostOrder = Arrays.copyOfRange(postorder,0,point);        int[] rightPostOrder = Arrays.copyOfRange(postorder,point,length-1);        TreeNode root = new TreeNode(rootVal);        root.left = buildTree(leftInOrder,leftPostOrder);        root.right = buildTree(rightInOrder,rightPostOrder);        return root;    }}