[LeetCode 106] Construct Binary Tree from Inorder and Postorder Traversal

题目链接：construct-binary-tree-from-inorder-and-postorder-traversal

import java.util.Arrays;

//根据中序和后序遍历构建二叉树

/**
 * 
 *	Given Inorder and Postorder traversal of a tree, construct the binary tree.
 * 
 *  Note: You may assume that duplicates do not exist in the tree.
 * 
 */

public class ConstructBinaryTreeFromInorderAndPostorderTraversal {

	public class TreeNode {
		int val;
		TreeNode left;
		TreeNode right;

		TreeNode(int x) {
			val = x;
		}
	}

//	202 / 202 test cases passed.
//	Status: Accepted
//	Runtime: 390 ms
//	Submitted: 0 minutes ago


    public TreeNode buildTree(int[] inorder, int[] postorder) {
		int len = postorder.length;
		if (len > 0) {
			TreeNode root = new TreeNode(postorder[len - 1]);
			int rootIndex = 0;
			// 找到根节点在中序遍历中的位置
			for (; rootIndex < len; rootIndex++) {
				if (inorder[rootIndex] == postorder[len - 1]) {
					break;
				}
			}

			// 分别构建左右子树
			root.left = buildTree(Arrays.copyOfRange(postorder, 0, rootIndex),
									Arrays.copyOfRange(inorder, 0, rootIndex));
			root.right = buildTree(Arrays.copyOfRange(postorder, rootIndex + 1, len),
									Arrays.copyOfRange(inorder, rootIndex, len - 1));

			return root;
		} else {
			return null;
		}
	}

	public static void main(String[] args) {
		// TODO Auto-generated method stub

	}

}

[LeetCode 106] Construct Binary Tree from Inorder and Postorder Traversal

原文：http://blog.csdn.net/ever223/article/details/44625313