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.
1 /** 2 * Definition for binary tree 3 * struct TreeNode { 4 * int val; 5 * TreeNode *left; 6 * TreeNode *right; 7 * TreeNode(int x) : val(x), left(NULL), right(NULL) {} 8 * }; 9 */ 10 class Solution { 11 public: 12 bool hasPathSum(TreeNode *root, int sum) { 13 if(!root) return false; 14 if(!root->left && !root->right) return sum == root->val; 15 return hasPathSum(root->left, sum-root->val) || 16 hasPathSum(root->right, sum-root->val); 17 } 18 };
原文：http://www.cnblogs.com/zhengjiankang/p/3649682.html