POJ 2785 4 Values whose Sum is 0

4 Values whose Sum is 0

Time Limit: 15000MS		Memory Limit: 228000K
Total Submissions: 17088		Accepted: 4998
Case Time Limit: 5000MS

Description

The SUM problem can be formulated as follows: given four lists A, B, C, D of integer values, compute how many quadruplet (a, b, c, d ) ∈ A x B x C x D are such that a + b + c + d = 0 . In the following, we assume that all lists have the same size n .

Input

The first line of the input file contains the size of the lists n (this value can be as large as 4000). We then have n lines containing four integer values (with absolute value as large as 2 ²⁸ ) that belong respectively to A, B, C and D .

Output

For each input file, your program has to write the number quadruplets whose sum is zero.

Sample Input

6
-45 22 42 -16
-41 -27 56 30
-36 53 -37 77
-36 30 -75 -46
26 -38 -10 62
-32 -54 -6 45

Sample Output

5

题目也是要用到二分来做，将A+B C+D分别存在两个数组里面，尝试了用vector 来做然后用find函数来搜索，结果tle，所以有些题目还是老老实实敲，不要搞些骚操作，目前了解的只有set集合类的find函数是二分查找，其它集合类都是用的头文件里面的find函数，比较耗时不推荐使用，但是还有一个小坑就在于，可能会有重复的值出现，所以要加上这些重复的可能；

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