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 a binary tree node. * struct TreeNode { * int val; * struct TreeNode *left; * struct TreeNode *right; * }; */ bool hasPathSum(struct TreeNode* root, int sum) { bool left, right; if(root == NULL) return false; else if(root->val == sum && root->left == NULL && root->right == NULL) return true; else { left = hasPathSum(root->left, sum - root->val); right = hasPathSum(root->right, sum - root->val); return (left || right); } }
原文：http://www.cnblogs.com/dylqt/p/4870143.html