Path Sum

一、题目要求

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.

二、代码实现

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