[USACO16OPEN]262144 P 题解

#include<cstdlib>
#include<cmath>
#include<ctime>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
#define LL long long
int f[59][262145]; 
int main()
{
	int n,x,ans=0;
	cin>>n;
	for(int i=1;i<=n;i++)
	{
		cin>>x;
		f[x][i]=i+1;
	}
	for(int i=2;i<=58;i++)
	for(int j=1;j<=n;j++)
	{
		if(!f[i][j])
		f[i][j]=f[i-1][f[i-1][j]];
		if(f[i][j]) 
		ans=i;
	}
	cout<<ans;
}