# 112. Path Sum
Difficulty: Easy

## Solution

/**
*** Author: R-CO
*** E-mail: [e-mail]
*** Date: 2020-11-11
**/
#include <cstdlib>
#include <iostream>
using std::cout;
using std::endl;

struct TestCasesStruct {};

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left),
 * right(right) {}
 * };
 */
struct TreeNode {
  int val;
  TreeNode *left;
  TreeNode *right;
  TreeNode() : val(0), left(nullptr), right(nullptr) {}
  TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
  TreeNode(int x, TreeNode *left, TreeNode *right)
      : val(x), left(left), right(right) {}
};

class Solution {
 public:
  bool hasPathSum(TreeNode* root, int sum) {
    bool result = false;
    
    preorderTraversal(root, sum, result);
    
    return result;
  }
 private:
  void preorderTraversal(TreeNode *node, int sum, bool &result) {
    if (node == nullptr) {
      return;
    }
    
    sum -= node->val;
    if (sum == 0 && node->left == nullptr && node->right == nullptr) {
      result = true;
      return;
    }
    
    preorderTraversal(node->left, sum, result);
    preorderTraversal(node->right, sum, result);
  }
};

int main(int argc, char *argv[]) { return EXIT_SUCCESS; }

## Result
Success
Details
Runtime: 4 ms, faster than 99.93% of C++ online submissions for Path Sum.
Memory Usage: 21.7 MB, less than 72.97% of C++ online submissions for Path Sum.

###### tags: `LeetCode-Easy` `C++`