【LeetCode】-Construct Binary Tree from Inorder and Postorder Traversal

Given inorder and postorder traversal of a tree, construct the binary tree.

Note:

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

/** * Definition for binary tree * public class TreeNode { *     int val; *     TreeNode left; *     TreeNode right; *     TreeNode(int x) { val = x; } * } */public class Solution {        private int getIndex( int[] nums, int element, int start, int end ){for( int i=start; i<=end; i++ ){if( element==nums[i] )return i;}return -1;}private TreeNode createTree( int[] in_arr, int in_start, int[] post_arr, int post_start, int length ){if( length<=0 )return null;TreeNode root = new TreeNode( post_arr[post_start+length-1] );int index = getIndex( in_arr, post_arr[post_start+length-1], in_start, in_start+length );int len = index - in_start;root.left = createTree( in_arr, in_start, post_arr, post_start, len );root.right = createTree( in_arr, index+1, post_arr, post_start+len, length-len-1 );return root;}    public TreeNode buildTree(int[] inorder, int[] postorder) {        if( inorder.length!=postorder.length )return null;return createTree( inorder, 0, postorder, 0, inorder.length );       }}