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.
/** * Definition for binary tree * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ public class Solution { public boolean hasPathSum(TreeNode root, int sum) { if(root==null){ return false; } int differ=sum-root.val; if(root.left==null&&root.right==null&&differ==0){ return true; } return hasPathSum(root.left,differ)||hasPathSum(root.right,differ); } }
原文：http://www.cnblogs.com/lilyfindjobs/p/4055692.html