Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.
For example:
Given the below binary tree and sum = 22,
5
/ 4 8
/ / 11 13 4
/ \ 7 2 1
return true, as there exist a root-to-leaf path 5->4->11->2 which sum is 22.
深度遍历解决，中序遍历代码如下：
/** * Definition for binary tree * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ public class Solution { //深度遍历二叉树 public boolean DFS(TreeNode node,int sum,int currentSum) { if(node==null) return false; if(node.left==null&&node.right==null) return (currentSum+node.val)==sum; else{ return DFS(node.left,sum,currentSum+node.val)||DFS(node.right,sum,currentSum+node.val); } } public boolean hasPathSum(TreeNode root, int sum) { return DFS(root,sum,0); } }
原文：http://www.cnblogs.com/mrpod2g/p/4292856.html