BZOJ 2795: [Poi2012]A Horrible Poem( hash )

#include<bits/stdc++.h>

using namespace std;

typedef unsigned long long ull;

const int maxn = 500009;
const ull P = 1000173169;

char S[maxn];
int check[maxn], prime[maxn], N = 0, n;
ull H[maxn], K[maxn];

void init() {
	memset(check, 0, sizeof check);
	for(int i = 2; i <= n; i++) {
		if(!check[i])
			check[i] = prime[N++] = i;
		for(int j = 0; j < N && i * prime[j] <= n; j++) {
			check[i * prime[j]] = prime[j];
			if(i % prime[j] == 0) break;
		}
	}
	H[n] = 0; K[0] = 1;
	for(int i = n - 1; ~i; i--)
	    H[i] = H[i + 1] * P + S[i];
	for(int i = 1; i <= n; i++)
	    K[i] = K[i - 1] * P;
}

inline bool jud(int a, int b, int L) {
	return H[a] - H[a + L] * K[L] == H[b] - H[b + L] * K[L];
}

void Read() {
	cin >> n;
	char* t = S;
	for(; !islower(*t); *t = getchar());
	for(int i = 1; i < n; i++)
	    *++t = getchar();
}

int main() {
	
	Read();
	init();
	
	int q; scanf("%d", &q);
	while(q--) {
		int l, r; scanf("%d%d", &l, &r); l--; r--;
		int ans = r - l + 1, t = ans;
		while(t > 1) {
			int x = check[t];
			while(ans % x == 0 && jud(l, l + ans / x, r - l  + 1 - ans / x)) ans /= x;
			for(; t % x == 0; t /= x);
		}
		printf("%d\n", ans);
	}
	
	return 0;
}