LeetCode OJ:Path Sum

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