Coprime Sequence                                                        Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 131072/131072 K (Java/Others)                                                                                      Total S…

Description Do you know what is called ``Coprime Sequence''? That is a sequence consists of $n$ positive integers, and the GCD (Greatest Common Divisor) of them is equal to 1. ``Coprime Sequence'' is easy to find because of its restriction. But we ca…

Do you know what is called ``Coprime Sequence''? That is a sequence consists of nn positive integers, and the GCD (Greatest Common Divisor) of them is equal to 1. ``Coprime Sequence'' is easy to find because of its restriction. But we can try to maxi…

Do you know what is called ``Coprime Sequence''? That is a sequence consists of nnpositive integers, and the GCD (Greatest Common Divisor) of them is equal to 1. ``Coprime Sequence'' is easy to find because of its restriction. But we can try to maxim…

题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=6025 Coprime Sequence Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 131072/131072 K (Java/Others) Total Submission(s): 666    Accepted Submission(s): 336 Problem Description Do you know what is…

HDU6025 Coprime Sequence 处理出数列的 \(gcd\) 前缀和后缀,删除一个数后的 \(gcd\) 为其前缀和后缀的 \(gcd\) . 遍历数列取 \(max\) 即为答案. 时间复杂度为 \(O(n)\) . #include<bits/stdc++.h> using namespace std; const int maxn = 100005; int a[maxn], head[maxn], tail[maxn]; int t, n; int gcd(int a…

题意:去除数列中的一个数字,使去除后数列中所有数字的gcd尽可能大. 分析:这个题所谓的Coprime Sequence,就是个例子而已嘛,题目中没有任何语句说明给定的数列所有数字gcd一定为1→_→,队友这样解读题目导致我们队的思路完全想歪了,当时真的脑子发懵,为啥没再读一遍题= = 1.求出一个数列的gcd跟计算顺序没关系. 2.如果求去掉下标为i的数字后整个数列的gcd,直接将该数字前的所有数字的gcd(prefix[i-1])和该数字后所有数字的gcd(suffix[i+1])再求一下g…

题意:给出一串数列,这串数列的gcd为1,要求取出一个数使取出后的数列gcd最大. 题解:可以通过对数列进行预处理,求出从下标为1开始的数对于前面的数的gcd(数组从下标0开始),称为前缀gcd,再以类似的方式求出后缀gcd,然后从第一个数开始枚举取出后的gcd(这个数的前缀gcd与后缀gcd的gcd).找出最大的gcd数即可. 代码如下: #include<cstdio> #include<cstring> #include<algorithm> using name…

枚举,预处理. 预处理前缀$gcd$与后缀$gcd$,枚举删哪一个即可. #include <bits/stdc++.h> using namespace std; int T,n; ]; ]; ]; long long gcd(long long a,long long b) { ) return a; return gcd(b,a%b); } int main() { scanf("%d",&T); while(T--) { scanf("%d&quo…

CO-PRIME 时间限制:1000 ms  |  内存限制:65535 KB 难度:3   描述 This problem is so easy! Can you solve it? You are given a sequence which contains n integers a1,a2……an, your task is to find how many pair(ai, aj)(i < j) that ai and aj is co-prime.   输入 There are mu…