2795: [Poi2012]A Horrible Poem

#include<bits/stdc++.h>
using namespace std;

typedef unsigned long long ull;

const int N=500009;
const ull B=1000173169;

int n,q;
int p
,lp
;
char S
;
bool vis
;
ull Base
,H
;

bool judge(int a,int b,int L){return H[a+L-1]-H[a-1]*Base[L]==H[b]-H[b-L]*Base[L];}

void euler()
{
for(int i=2;i<=n;i++){
if(!vis[i]) lp[i]=i,p[++p[0]]=i;
for(int j=1;j<=p[0]&&i*p[j]<=n;j++)
{
vis[i*p[j]]=1;lp[i*p[j]]=p[j];
if(i%p[j]==0) break;
}
}
Base[0]=1;for(int i=1;i<=n;i++) Base[i]=Base[i-1]*B,H[i]=H[i-1]*B+S[i];
}

void work()
{
for(scanf("%d",&q);q;q--){
int l,r;scanf("%d%d",&l,&r);
int now=r-l+1,v=now;
while(v!=1){
if(judge(l,r,r-l+1-now/lp[v])) now/=lp[v];
v/=lp[v];
}
printf("%d\n",now);
}
}

void init()
{
scanf("%d%s",&n,S+1);
euler();
}

int main()
{
init();
work();
return 0;
}