Path Sum

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