leetcode[112]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 hasPathSum(TreeNode *root, int sum) {

        if(root==NULL)return false;

        if(root->left==NULL&&root->right==NULL)return root->val==sum;

/*

        if(root->left!=NULL&&root->right==NULL)return hasPathSum(root->left,sum-root->val);

        if(root->left==NULL&&root->right!=NULL)return hasPathSum(root->right,sum-root->val);

*/

        return hasPathSum(root->left,sum-root->val)||hasPathSum(root->right,sum-root->val);

    }

};