https://leetcode.com/problems/3sum-closest/

3sum-closest.cpp

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

class Solution {
public:
    int threeSumClosest(vector<int> nums, int target)
    {
        if (nums.size() < 3) return target;
        sort(nums.begin(), nums.end());

        int closest = nums[0] + nums[1] + nums[2];
        for (size_t i = 0; i < nums.size() - 2; i++)
        {
            int font = i + 1;
            int back = nums.size() - 1;

            while (font < back)
            {
                int sum = nums[i] + nums[font] + nums[back];
                if (sum == target) return target;
                if (abs(sum - target) < abs(closest - target)) closest = sum;
                if (sum > target) back--;
                else font++;
            }
        }
        return closest;
    }
};

int main()
{
    Solution a;
    auto b = a.threeSumClosest({ 1, 2, 4, 8, 16, 32, 64, 128 }, 82);
    return 0;
}