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.

              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
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    bool check(TreeNode *root, int sum, int cursum){
        if(root==NULL) return false;
        if(root->left==NULL && root->right==NULL) {
            if(cursum+root->val==sum) return true;
            else return false;
        }
        return (check(root->left,sum,cursum+root->val)||check(root->right,sum,cursum+root->val));
    }
    bool hasPathSum(TreeNode *root, int sum) {
        return check(root,sum,0);
    }
};

Path Sum