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 pathsum(TreeNode *root,int sum,int val) 13 { 14 if(root==NULL)return 0; 15 val+=root->val; 16 if(root->left==NULL&&root->right==NULL) 17 { 18 if(sum==val)return 1; 19 return 0; 20 21 } 22 23 return pathsum(root->left,sum,val)||pathsum(root->right,sum,val); 24 25 26 } 27 28 29 bool hasPathSum(TreeNode *root, int sum) { 30 31 return pathsum(root,sum,0); 32 } 33 };
原文：http://www.cnblogs.com/jawiezhu/p/4486988.html