cpp, LeetCode, C++

Two Sum solution on Leet Code

The simple solution

class Solution {
public:
    vector<int> twoSum(vector<int>& nums, int target) {
        for (int i = 0; i < nums.size(); ++i)
        {
            for (int j = i + 1; j < nums.size(); ++j)
            {
                if (nums.at(i) + nums.at(j) == target)
                {
                    return {i,j};
                }
            }
        }
        return {};
    }
};

Solution using map

class Solution {
public:
    vector<int> twoSum(vector<int>& nums, int target) {
        int n = nums.size();
        std::map<int, int> targets;

        for (int i = 0; i < n; ++i)
        {
            if (targets.count(nums[i]) && targets[nums[i]] != i)
            {
                return {targets[nums[i]], i};
            }
            targets[target - nums[i]] = i;
        }

        return {};
    }
};