题意 Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in the array which gives the sum of target. 给定一个数组,找出其中的四个数,使它们的和等于某个特定的数 解法 和2Sum以及3Sum一样,都是先排序然后遍历前面几个数,剩下的两个数用T…