Two Sum · Embed | Leonardo Wajda

    
package array.iterative;

import java.util.HashMap;
import java.util.Map;

public class TwoSum {
    public int[] twoSum(int[] nums, int target) {

        Map<Integer, Integer> map = new HashMap<>();
        for (int i = 0; i < nums.length; i++) {
            int complement = target - nums[i];
            if (map.containsKey(complement))
                return new int[] { map.get(complement), i };
            map.put(nums[i], i);
        }

        return new int[] { -1, -1 };
    }
}

class TwoSum:
    def twoSum(self, nums: list[int], target: int) -> list[int]:
        index_by_value: dict[int, int] = {}

        for index, value in enumerate(nums):
            complement = target - value
            match_index = index_by_value.get(complement)
            if match_index is not None:
                return [match_index, index]

            index_by_value[value] = index

        return [-1, -1]

#include <unordered_map>
#include <vector>

class TwoSum {
 public:
  std::vector<int> twoSum(const std::vector<int>& nums, const int target) const {
    std::unordered_map<int, int> index_by_value;
    index_by_value.reserve(nums.size());
    const auto size = static_cast<int>(nums.size());

    for (int index = 0; index < size; ++index) {
      const int value = nums[index];
      const int complement = target - value;
      const auto match = index_by_value.find(complement);

      if (match != index_by_value.end())
        return {match->second, index};

      index_by_value[value] = index;
    }

    return {-1, -1};
  }
};