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LeetCode solutions

1. Two Sum

My accepted C++ and Python solution to LeetCode problem 1, Two Sum, running in 0ms.

  • Difficulty: Easy
  • C++
  • Python
  • Runtime 0ms
  • Memory 15MB

Read the problem on LeetCode View on GitHub

The problem statement is LeetCode’s and stays on their site. What follows is my accepted solution.

C++

Accepted on LeetCode — runtime 0ms, memory 15MB, accepted 2025-12-28.

cpp
class Solution {
    public:
    vector<int> twoSum(vector<int>& nums, int target) {
        unordered_map<int, int> mp;
        for (int i = 0; i < nums.size(); i++) {
            int complement = target - nums[i];
            if (mp.count(complement)) {
                return {mp[complement], i};
            }
            mp[nums[i]] = i;
        }
        return {};

    }
};

Python

Accepted on LeetCode — runtime 0ms, memory 13.2MB, accepted 2025-12-23.

python
class Solution(object):
    def twoSum(self, nums, target):
        num_map = {}
        for i, num in enumerate(nums):
            complement = target - num
            if complement in num_map:
                return [num_map[complement], i]
            num_map[num] = i

Source