浙江中医药大学暑期训练测试赛八F

最新推荐文章于 2017-08-16 17:31:42 发布

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最新推荐文章于 2017-08-16 17:31:42 发布

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本文探讨了如何求解一个整数数组中最大的连续子数组，使得该子数组的所有元素的最大公约数(GCD)为1的问题。介绍了问题背景、输入输出格式及样例，并给出了使用辗转相减法实现的AC代码。

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1571: Subarray GCD

Time Limit: 1 Sec Memory Limit: 128 MB
Submit: 90 Solved: 48
[ Submit][ Status][ Web Board]

Description

Given an array A₁,A₂...A_N, you have to print the size of the largest contiguous subarray such that
GCD of all integers in that subarray is 1.

Formally,
For a subarray A_i,A_i+1...A_j where 1 ≤ i < j ≤ N to be valid: GCD(A_i,A_i+1...A_j) should be 1. You have to print the size of the largest valid subarray.

If no valid subarray exists, output -1.

Note:A single element is not considered as a subarray according to the definition of this problem.

Input

First line contains T, the number of testcases. Each testcase consists of N in one line followed by Nintegers in the next line.

Constraints

1 ≤ T ≤ 10
2 ≤ N ≤ 10⁵
1 ≤ A_i ≤ 10⁵

Output

For each testcase, print the required answer in one line.

Sample Input

7 2

2 2 4

Sample Output

-1

AC代码：

#include<iostream>
#include<algorithm>
#include<string.h>
#include<stdio.h>
using namespace std;
int gcd(int a,int b)
{
while(b)//辗转相减法
{
int temp=a%b;
a=b;
b=temp;
}
return a;
}
int main()
{
int t;
scanf("%d",&t);
while(t--)
{
int n;
scanf("%d",&n);
int x;
scanf("%d",&x);
for(int i=1;i<n;i++)
{
int temp;
scanf("%d",&temp);
x=gcd(x,temp);
}
if(x==1)
printf("%d\n",n);
else
printf("-1\n");
}
return 0;
}