Submission #866329

#	Time	Username	Problem	Language	Result	Execution time	Memory
866329		nikuradze	Necklace (Subtask 1-3) (BOI19_necklace1)	C++14	0 / 85	1 ms	348 KiB

necklace

/*
Я русский,
     Я иду до конца.
     Я русский,
     Моя кровь от Отца.

     Я русский,
     И мне повезло.
     Я русский,
     Всему миру назло.

     Я русский!
*/
//#pragma GCC optimize("O3")'
#pragma GCC optimize("Ofast")
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#include <cstdio>
#include <cmath>
#include <set>
#include <vector>
#include <iostream>
#include <algorithm>
#include <map>
using namespace std;
#define double long double
//#define int long long
using ll = long long;
const int mod = 1e9 + 7;
const int mod9 = 1e9 + 9;
const ll MAXN = 1e6 + 100;
const int MAXB = 8;
const int MAXL = 1e6 + 1e5;
#ifndef ONLINE_JUDGE
#define debug(x) cerr << (#x) << ": " << x << endl;
#else
#define debug(x)
#endif
int bin_pow(int x, int e) {
    int c = x, r = 1;
    for (; e; e >>= 1, c = c * 1LL * c % mod) {
        if (e & 1) r = r * 1LL * c % mod;
    }
    return r;
}
int rev(int a) {
    return bin_pow(a, mod - 2);
}
int make_add(int x, int y) {
    if ((ll)x + y >= mod) return x + y - mod;
    return x + y;
}
int mul(int x, int y) {
    ll p = (ll(x)) * y;
    return p % mod;
}
int gcd(int a, int b) {
    while (a > 0 && b > 0) {
        int c = a;
        a = b % a;
        b = c;
    }
    return a + b;
}
const int base = 61;
struct hashes {
    vector<int> power;
    vector<int> pref;
    void init(string s, int m) {
        int n = s.size();
        pref = vector<int>(n + 1);
        power = vector<int>(n + 1);
        power[0] = 1;
        for (int i = 0; i < n; i++) {
            pref[i + 1] = (pref[i] * base + s[i] - 96) % m;
            power[i + 1] = (power[i] * base) % m;
        }
    }
    int get(int i, int j, int m) {
        int ans = (pref[j] - (pref[i] * (power[j - i]) % m) + m) % m;
        return ans;
    }
};
int get_st(string s, string t) {
    int n = s.size(), m = t.size();
    set<pair<int, int> > all_hash_s;
    for (int i = 0; i < n; i++) {
        string add;
        for (int j = i; j < n; j++) {
            add += s[j];
            string cadd = add;
            add = add + add;
            hashes m7, m9;
            m7.init(add, mod);
            m9.init(add, mod9);
            for (int p = 0; p < cadd.size(); p++) {
                int l = p, r = p + cadd.size();
                int hash7 = m7.get(l, r, mod), hash9 = m9.get(l, r, mod9);
                all_hash_s.insert({ hash7, hash9 });
            }
            add = cadd;
        }
    }
    int mx = 0;
    for (int i = 0; i < m; i++) {
        string add;
        for (int j = i; j < m; j++) {
            add += t[j];
            string cadd = add;
            add = add + add;
            hashes m7, m9;
            m7.init(add, mod);
            m9.init(add, mod9);
            for (int p = 0; p < cadd.size(); p++) {
                int l = p, r = p + cadd.size();
                int hash7 = m7.get(l, r, mod), hash9 = m9.get(l, r, mod9);
                if (all_hash_s.count({ hash7,hash9 })) {
                    mx = max(mx, j - i + 1);
                    break;
                }
            }
            add = cadd;
        }
    }
    return mx;
}
int stupid(string s, string t) {
    int mx1 = get_st(s, t);
    reverse(t.begin(), t.end());
    int mx2 = get_st(s, t);
    return max(mx1, mx2);
}
vector<int> prefix_function(string s) {
    int n = (int)s.length();
    vector<int> pi(n);
    for (int i = 1; i < n; ++i) {
        int j = pi[i - 1];
        while (j > 0 && s[i] != s[j])
            j = pi[j - 1];
        if (s[i] == s[j])  ++j;
        pi[i] = j;
    }
    return pi;
}
int get(string s, string t) {
    int n = s.size(), m = t.size();
    vector<vector<int> > pre_prefix_func;
    for (int i = 0; i <= m; i++) {
        string cur;
        for (int j = 0; j < n; j++) cur += s[j];
        cur += '#';
        for (int j = 0; j < i; j++) {
            cur += t[j];
        }
        reverse(cur.begin(), cur.end());
        vector<int> p = prefix_function(cur);
        pre_prefix_func.push_back(p);
    }
    int ans = 0;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < 1; j++) {
            string to_ab;
            for (int p = i; p < n; p++) to_ab += s[p];
            to_ab += '#';
            for (int p = 0; p < m; p++) to_ab += t[p];
            vector<int> ab = prefix_function(to_ab);
            int sz = ab.size();
            int what_to_n = n - i;
            for (int p = what_to_n + 1; p < sz; p++) {
                int cur_add = ab[p];
                //if (cur_add != p - what_to_n) continue;               
                int ind = p - what_to_n - cur_add;
                int pos = cur_add + i + 1;
                pos = ind + 1 + n - pos;
                int may = pre_prefix_func[ind][pos];
                ans = max(ans, may + cur_add);
            }
        }
    }
    return ans;
}
int clever(string s, string t) {
    int mx1 = get(s, t);
    reverse(t.begin(), t.end());
    int mx2 = get(s, t);
    return max(mx1, mx2);
}
void solve() {
    string s, t;
    cin >> s >> t;
    int mx1 = get(s, t);
    reverse(t.begin(), t.end());
    int mx2 = get(s, t);
    cout << max(mx1, mx2);
}
void gen() {
    string s, t;
    int n = rand() % 5 + 1, m = rand() % 5 + 1;
    for (int i = 0; i < n; i++) {
        int r = rand() % 3;
        s += (char)(r + 97);
    }
    for (int i = 0; i < m; i++) {
        int r = rand() % 3;
        t += (char)(r + 97);
    }
    int st = stupid(s, t);
    int cl = clever(s, t);
    if (st != cl) {
        cout << s << " " << t << endl;
        cout << st << " " << cl << endl;
        exit(0);
    }
}
int num = 0;
signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int t = 1 - 1 + 1;
    /*
    while (true) {
        debug(num++);
        gen();
    }
    */
    // cin >> t;
    while (t--) {
        solve();
    }
}
/*
acccb 
ccabc
*/

Compilation message (stderr)

necklace.cpp: In function 'int get_st(std::string, std::string)':
necklace.cpp:96:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   96 |             for (int p = 0; p < cadd.size(); p++) {
      |                             ~~^~~~~~~~~~~~~
necklace.cpp:114:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  114 |             for (int p = 0; p < cadd.size(); p++) {
      |                             ~~^~~~~~~~~~~~~

• Subtask 1: 0 / 25
• Subtask 2: 0 / 20
• Subtask 3: 0 / 40