[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.

[Solution].java

/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public TreeNode buildTree(int[] inorder, int[] postorder) {
        // Start typing your Java solution below
        // DO NOT write main() function
        return buildTree(0, inorder.length - 1, 0, postorder.length - 1,
            inorder, postorder);
    }

    public TreeNode buildTree(int inBegin, int inEnd, int posBegin, int posEnd,
      	int[] inorder, int[] postorder){
    	if(posBegin > posEnd) return null;
    	int mid = inBegin;
    	for(; mid <= inEnd; mid++) if(postorder[posEnd] == inorder[mid]) break;
    	TreeNode parent = new TreeNode(inorder[mid]);
    	parent.left = buildTree(inBegin, mid - 1, posBegin, posBegin + mid - inBegin - 1,
    		inorder, postorder);
    	parent.right = buildTree(mid + 1, inEnd, posBegin + mid - inBegin, posEnd - 1,
    		inorder, postorder);
    	return parent;

    }
}