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 andsum = 22, 5 /
4 8 / /
11 13 4 /
7 2 1 return true, as there exist a root-to-leaf path5->4->11->2which sum is 22.
C++
/**
* Definition for binary tree
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
bool hasPathSum2(TreeNode *root, int sum) {
if(NULL == root) return false;
if(NULL == root->left && NULL == root->right && sum == root->val) return true;
if(NULL != root->left && hasPathSum(root->left,sum-root->val)) return true;
if(NULL != root->right && hasPathSum(root->right,sum-root->val)) return true;
return false;
}
bool hasPathSum(TreeNode *root, int sum) {
if(NULL == root) return false;
if(NULL == root->left && NULL == root->right && sum == root->val) return true;
return hasPathSum(root->left,sum-root->val) || hasPathSum(root->right,sum-root->val);
}
};