leetcode_1.cpp

// LeetCode Problem 1: Two Sum
// Given an array of integers, return indices of the two numbers such that they add up to a specific target.
// You may assume that each input would have exactly one solution, and you may not use the same element twice.
// You can return the answer in any order.
// Example: Input: nums = [2,7,11,15], target = 9; Output: [0,1] (because nums[0] + nums[1] = 9)
class Solution
{
public:
  // Function that takes a vector of integers and a target sum, returns indices of two numbers that add up to target
  vector<int> twoSum(vector<int> &nums, int target)
  {
    // Create an empty vector to store the result indices
    vector<int> myarr;

    // Outer loop - pick the first number
    for (int i = 0; i < nums.size(); i++)
    {
      // Inner loop - pick the second number (starts from i+1 to avoid using same element twice)
      for (int j = i + 1; j < nums.size(); j++)
      {

        // If the sum of two numbers equals target
        if (nums[i] + nums[j] == target)
        {
          myarr.push_back(i); // Add first index to result
          myarr.push_back(j); // Add second index to result
          return myarr;       // Return the result immediately when found
        }
      }
    }

    // If no solution is found, return empty vector
    return {};
  }
};