[LeetCode16]3Sum Closed

题目来源：点击打开链接https://leetcode.com/problems/3sum-closest/

Given an array S of n integers, find three integers in S such that the sum is closest to a given number, target. Return the sum of the three integers. You may assume that each input would have exactly one solution.

    For example, given array S = {-1 2 1 -4}, and target = 1.

    The sum that is closest to the target is 2. (-1 + 2 + 1 = 2).

class Solution16{
public:
	int threeSumClosest(vector<int>& nums, int target){
		int result = 0;
		int min_gap = INT_MAX;

		sort(nums.begin(), nums.end());

		for (auto i = nums.begin(); i != prev(nums.end(), 2); ++i){
			
			auto j = next(i);
			auto k = prev(nums.end());

			while (j < k){
				int sum = *i + *j + *k;
				int gap = abs(sum - target);

				if (gap < min_gap){
					result = sum;
					min_gap = gap;
				}

				if (sum < target)++j;
				else --k;
			}		
		}
		return result;
	}
};

int main16(){

	Solution16 solution;
	vector<int> nums = {-1,2,4,1};
	int target = 1;
	cout<<solution.threeSumClosest(nums, target);

	getchar();
	return 0;
}