TIOJ 1515 (TLE...)

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define SZ(X) ((int)(X).size())

int modmul(int A, int B, int mod)
{
    return (A*B-(int)((long double)A*B/mod)*mod+mod)%mod;
}

class Strhash{
    private:
        vector<long long> hash, pows;
        const long long mod = 304250263527209;
    public:
        Strhash(string s, int prm=0xdefaced){
            hash.emplace_back(0);
            pows.emplace_back(1);
            for(unsigned i = 0; i < s.size(); ++i){
                hash.emplace_back((hash.back()*prm+s[i])%mod);
                pows.emplace_back(pows.back()*prm%mod);
            }
        }
        Strhash(char *c, int prm=0xdefaced){
            hash.emplace_back(0);
            pows.emplace_back(1);
            for(int i = 0; c[i] != '\0'; ++i){
                hash.emplace_back((hash.back()*prm+c[i])%mod);
                pows.emplace_back(pows.back()*prm%mod);
            }
        }
        long long gethash(int l, int r){//[l,r)
            return (hash[r]+mod-modmul(hash[l], pows[r-l], mod))%mod;
        }
};

int same[200000];

int32_t main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int small=1, big;
    string s;
    cin >> big >> s;
    Strhash tool(s, 10079);
    while(big >= small){
        int cnt = 0;
        int mid = (big + small) / 2;
        for(int i = 0; i+mid <= SZ(s); ++i){
            same[cnt++] = tool.gethash(i, i+mid);
        }
        sort(same, same+cnt);
        if(unique(same, same+cnt)-same == cnt){
            big = mid - 1;
        }else{
            small = mid + 1;
        }
        //cout << SZ(same ) << ' ' << mid << '\n';
    }
    cout << big << '\n';
    return 0;
}