4 Values whose Sum is 0 Time Limit: 15000MS Memory Limit: 228000K Total Submissions: 19322 Accepted: 5778 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 man…

题目链接:http://poj.org/problem?id=2785 题意是给你4个数列.要从每个数列中各取一个数,使得四个数的sum为0,求出这样的组合的情况个数. 其中一个数列有多个相同的数字时,把他们看作不同的数字. 做法是把前两个数列和的值存在一个数组(A)中 , 后两个数列的和存在另一个数组(B)中 , 数组都为n^2 . 然后将B数组sort一下 , 将A数组遍历 , 二分查找一下B数组中与A数组元素和为0的个数 . 有个注意的点是万一A数组都是0 , 而B数组都为0的情况(还有其…

题目链接:https://cn.vjudge.net/problem/POJ-2785 题意 给出四组数,每组有n个数 现从每组数中取一个数作为a,b,c,d 问有几组这样的a+b+c+d=0 思路 首先把第一组和第二组的和添加在hash表里 再枚举三组四组的和,查找即可 代码 #include <cstdio> #include <cstring> const int hashSize=int(4e5), idxSize=int(1.6e7); struct Data{ int…

http://poj.org/problem?id=2785 题目大意: 给你四个数组a,b,c,d求满足a+b+c+d=0的个数 其中a,b,c,d可能高达2^28 思路: 嗯,没错,和上次的 HDU 1496 Equations hash(见http://blog.csdn.net/murmured/article/details/17596655)差不多,但是那题数据量小,hash值很好得到,不用取模运算. 而这题数据量很大.那就采用开散列的思想. hash值怎么选取? 上次我看的书中是建…

题意:给你四组长度为\(n\)序列,从每个序列中选一个数出来,使得四个数字之和等于\(0\),问由多少种组成情况(仅于元素的所在位置有关). 题解:\(n\)最大可以取4000,直接暴力肯定是不行的,我们可以先对后两个数组\(c\)和\(d\),枚举他们每个元素的和,用一个新数组\(CD\)记录,然后再去枚举\(a\)和\(b\)的和,那么我们只要在\(CD\)中二分查找\(a\)和\(b\)的和的相反数就好了. 代码: #include <iostream> #include <cst…

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 .…

4 Values whose Sum is 0 Time Limit: 15000MS   Memory Limit: 228000K Total Submissions: 13069   Accepted: 3669 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…

4 Values whose Sum is 0 Time Limit: 15000MS   Memory Limit: 228000K Total Submissions: 23757   Accepted: 7192 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…

传送门 4 Values whose Sum is 0 Time Limit: 15000MS   Memory Limit: 228000K Total Submissions: 20334   Accepted: 6100 Case Time Limit: 5000MS Description The SUM problem can be formulated as follows: given four lists A, B, C, D of integer values, compute…

4 Values whose Sum is 0 Time Limit: 15000MS Memory Limit: 228000K Total Submissions: 17875 Accepted: 5255 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 man…