Path Sum Total Accepted: 50216 Total Submissions: 168425，50216submissions

Path Sum Total Accepted: 50216 Total Submissions: 168425，50216submissions

題目來自於leetcode

https://leetcode.com/problems/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:   void psum(TreeNode *root, int sum)    {       if(root!=NULL)       {          if(root->val==sum&&root->left==NULL&&root->right==NULL)        {            flag=true;            return ;        }                  psum(root->left,  sum-root->val);          psum(root->right,  sum-root->val);          //return false;         }              }    bool hasPathSum(TreeNode *root, int sum) {       if(root==NULL)        return false;         psum(root, sum) ;         return flag;    }        bool flag=false;};