2011: Permutation

2011: Permutation


Result TIME Limit MEMORY Limit Run Times AC Times JUDGE
5s 8192K 749 218 Standard

There are a group of strange people live in a strange island, where every morning each people gives his shoes(the unique) to his best friend(also the unique). Different people have different best friends. After a certain amount of days, they finally find that all the shoes come to their original owners. But they forget how many days have passed, so they ask Mr. Jojer, the most clever programmer, to find the least possible number of days.

Input and Output

The input may contain several test cases. Each test case contains an integer N(<30000) indicating the number of people(numbered by 1,2,…N) lived in the island. The following line of each test case contains N integers(range from 1 to N), the i th of which indicates the best friend of the person who is numbered by i.

For each test case, you should print the least possible number of days in a single line.

Sample Input

2
2 1

Sample Output

2
#include
int gcd(int x,int y)
{
    if(y==0) return x;
    return gcd(y,x%y);
}
int main()
{
    int f[30000];
    int n,i,j;
    while(scanf("%d",&n)==1)
    {
        int b[30000]={0},t=1;
        for(i=1;i<=n;i++) scanf("%d",&f[i]);
        for(i=1;i<=n;i++)
        {
            if(b[i]==0)
            {
                int ci=0;j=i;
                while(b[j]==0)
                {
                    ci++;
                    b[j]=1;
                    b[j]=1;
                    j=f[j];
                }
                t=t*ci/gcd(t,ci);
            }
        }
        printf("%d/n",t);
    }
    return 0;
}

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