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…

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…

C HDU - 6025 [题意]:去除数列中的一个数字,使去除后的数列中所有数字的gcd尽可能大. [分析]: 数组prefixgcd[],对于prefixgcd[i]=g,g为a[0]-a[i]的GCD,称为前缀GCD. 数组suffixgcd[],对于suffixgcd[i]=g,g为a[i]-a[n-1]的GCD,称为后缀GCD. 有了这两个GCD值的数组,那么去掉a[i]的GCD为gcd(prefixgcd[i - 1], suffixgcd[i + 1]),从中找出最大值即可. [代…

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: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…

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

题目链接: D. "Or" Game time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output You are given n numbers a1, a2, ..., an. You can perform at most k operations. For each operation you can multiply o…

[前后缀枚举] #include<cstdio> #include<string> #include<cstdlib> #include<cmath> #include<iostream> #include<cstring> #include<set> #include<queue> #include<algorithm> #include<vector> #include<map…