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

Given an arraySofnintegers, find three integers inSsuch 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).

基本和 3Sum一样， 只是这里closest，其实就是找绝对值最小的sum，|delta| close to 0.