[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.

    bool hasPathSum(TreeNode* root, int sum) {        if (root == nullptr) return false;        if (root->left == nullptr && root->right == nullptr)            return sum - root->val == 0;        int rest = sum - root->val;        if (hasPathSum(root->left, rest))            return true;        if (hasPathSum(root->right, rest))            return true;        return false;    }