牛客网Bogo Sort

题目描述：

Today Tonnnny the monkey learned a new algorithm called Bogo Sort. The teacher gave Tonnnny the code of Bogo sort:

The teacher said the shuffle function is to uniformly randomly permute the array $a\$ with length $n\$ , and the algorithm's expectation complexity is

\cdot n!)O(n⋅n!).

However, Tonnnny is a determined boy — he doesn't like randomness at all! So Tonnnny improved Bogo Sort. He had chosen one favourite permutation $p\$ with length $N\$ , and he replaced the random shuffle with shuffle of $p\$ , so the improved algorithm, Tonnnny Sort, can solve sorting problems for length $N\$ array — at least Tonnnny thinks so.

Tonnnny was satsified with the new algorithm, and decided to let you give him a different array of length $N\$ every day to sort it with Tonnnny Sort.

You are the best friend of Tonnnny. Even though you had found the algorithm is somehow wrong, you want to make Tonnnny happy as long as possible. You're given $pN,\ pN, p, and you need to calculate the maximum number of days that Tonnnny will be happy, since after that you can't give Tonnnny an array that can be sorted with Tonnnny Sort and didn't appeared before.$

The answer may be very large. Tonnnny only like numbers with at most $N\$ digits, so please output answer mod $10N10^N10N instead.$

6
2 3 4 5 6 1
输出2：
6

首先这题需要高精度。就尼玛恶心。
之后脑袋一拍我们就知道这题需要找到环的长度的；
并且求出这些环长度的最小公倍数；
然后就没有然后了。

上代码：

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#include<bits/stdc++.h>
using namespace std;
int n,m;
int len=1;
int sum,tot;
int z[100100];
int za[100100];
int s[1000010];
int v[1000010];
int a[1000010];
int ans[1000010];
void add(int x)
{
    for (int i=1; i<=len; i++) ans[i]*=x;
    for (int i=1; i<len; i++) ans[i+1]+=ans[i]/10,ans[i]%=10;
    while (len<n && ans[len]>=10) ans[len+1]+=ans[len]/10,ans[len]%=10,len++;
    ans[len+1]=0;
}
int main()
{
    for (int i=2; i<1e5+10; i++)
    {
        int f=0,num=0;
        for (int j=1; j*j<=i; j++)
        {
            if (i%j==0) num++;
            if (num>1)
            {
                f=1;
                break;
            }
        }
        if (f==1) continue;
        sum++;
        z[sum]=i;
    }
    ans[1]=1;
    v[1]=1;
    cin>>n;
    for (int i=1; i<=n; i++) scanf("%d",&a[i]);
    for (int i=1; i<=n; i++)
        if (v[i]==0)
        {
            v[i]=1;
            s[++tot]=1;
            for (int j=a[i]; j!=i; j=a[j])
                v[j]=1,s[tot]++;
        }
    for (int i=1; i<=tot; i++)
    {
        for (int j=1; j<=sum; j++)
        {
            int num=0;
            while (s[i]%z[j]==0) num++,s[i]/=z[j];
            za[j]=max(num,za[j]);
            m=max(j,m);
        }
    }
    for (int i=1; i<=m; i++)
    for (int j=1; j<=za[i]; j++)
        add(z[i]);
    for (int i=len; i>=1; i--) cout<<ans[i]%10;
}//有点丑别建议；

View Code

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