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.

Note: A leaf is a node with no children.

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.

题解：

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