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.

 

Code:

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/**  * 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 hasPathSum(TreeNode *root, int sum) {         if(!root)             return false;         if(!root->left&&!root->right&&root->val==sum)             return true;         else             return hasPathSum(root->left,sum-root->val)||hasPathSum(root->right,sum-root->val);     } };