Detection of secret messages

#include<bits/stdc++.h>

using namespace std;

const int N = 1e6 + 5;
const int M = 1002;
const int prime1 = 13;
const int mod1 = 1e9 + 7;

int n;
char text[N];
char s[M];

int binpow(int a, int n, int mod) {
    int res = 1;
    while (n) {
        if (n & 1)
            res = (1ll * res * a) % mod;
        a = (1ll * a * a) % mod;
        n >>= 1;
    }
    return res;
}

int main() {
    gets(text);

    int len = strlen(text);

    int n, l;
    scanf("%d%d", &n, &l);

    vector <int> vec;
    int hash1 = 0;
    for (int i = 0; i < l; i++) {
        hash1 = (1ll * text[i] * binpow(prime1, i + 1, mod1) + hash1) % mod1;
    }
    vec.push_back(hash1);

    for (int i = l; i <= len; i++) {
        hash1 = (1ll * hash1 * binpow(prime1, mod1 - 2, mod1)) % mod1;

        hash1 -= text[i - l];

        if (hash1 < 0) hash1 += mod1;

        hash1 = (1ll * text[i] * binpow(prime1, l, mod1) + hash1) % mod1;
        vec.push_back(hash1);
    }

    sort(vec.begin(), vec.end());

    for (int i = 0; i < n; i++) {
        getchar();
        int hs1 = 0;
        for (int j = 0; j < l; j++) {
            scanf("%c", &s[j]);
            hs1 = (1ll * s[j] * binpow(prime1, j + 1, mod1) + hs1) % mod1;
        }

        int lo = 0, hi = (int)vec.size() - 1;

        while (lo <= hi) {
            int md = (lo + hi) >> 1;
            if (vec[md] < hs1)
                lo = md + 1;
            else
                hi = md - 1;
        }

        if (vec[lo] == hs1) {
            puts("Yes");
        } else {
            puts("No");
        }
    }
}