leetcode_112_Path Sum

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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.

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