Submission #503282

#	Time	Username	Problem	Language	Result	Execution time	Memory
503282		Victor	Necklace (Subtask 1-3) (BOI19_necklace1)	C++17	45 / 85	1569 ms	588 KiB

necklace

// #pragma GCC target ("avx,avx2,fma")
// #pragma GCC optimize ("Ofast,inline") // O1 - O2 - O3 - Os - Ofast
// #pragma GCC optimize ("unroll-loops")
#include <bits/stdc++.h>

using namespace std;

#define rep(i, a, b) for (int i = (a); i < (b); ++i)
#define per(i, a, b) for (int i = (b - 1); i >= (a); --i)
#define trav(a, x) for (auto &a : x)

#define all(x) x.begin(), x.end()
#define sz(x) x.size()
#define pb push_back
#define debug(x) cout << #x << " = " << x << endl

#define umap unordered_map
#define uset unordered_set

typedef pair<int, int> ii;
typedef pair<int, ii> iii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<vi> vvi;

typedef long long ll;
typedef pair<ll, ll> pll;
typedef vector<ll> vll;
typedef vector<pll> vpll;

const ll INF = 1'000'000'007, MAXN = 3000;
const ll num_bases = 2, bases[] = {31, 47};
ll base_pow[num_bases][MAXN];

string jill, jane;

int main() {
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.failbit);

    rep(i, 0, num_bases) base_pow[i][0] = 1;
    rep(i, 0, num_bases) rep(j, 1, MAXN) base_pow[i][j] = base_pow[i][j - 1] * bases[i] % INF;

    cin >> jill >> jane;

    map<ii, int> possible;
    int n = min(sz(jill), sz(jane));

    per(mid, 1, n + 1) {
        vll hash_val = {0, 0};
        rep(j, 0, num_bases) rep(i, 0, mid - 1) hash_val[j] = (hash_val[j] * bases[j] + jill[i]) % INF;
        rep(i, mid - 1, sz(jill)) {
            rep(j, 0, num_bases) hash_val[j] = (hash_val[j] * bases[j] + jill[i]) % INF;

            possible.insert({{hash_val[0], hash_val[1]}, i - mid + 1});
            rep(j, 0, num_bases) hash_val[j] = ((hash_val[j] - base_pow[j][mid - 1] * jill[i - mid + 1]) % INF + INF) % INF;
        }

        int sjill = -1, sjane = -1;
        rep(k, 0, 2) {
            hash_val = {0, 0};
            rep(j, 0, num_bases) rep(i, 0, mid - 1) hash_val[j] = (hash_val[j] * bases[j] + jane[i]) % INF;
            rep(i, mid - 1, sz(jane)) {
                rep(j, 0, num_bases) hash_val[j] = (hash_val[j] * bases[j] + jane[i]) % INF;

                vll tmp_val = hash_val;
                rep(j, 0, mid) {
                    if (possible.count({tmp_val[0], tmp_val[1]})) {
                        if (k) {
                            sjane = i - mid + 1;
                            sjane = sz(jane) - sjane;
                            sjane -= mid;
                        } else
                            sjane = i - mid + 1;
                        sjill = possible[{tmp_val[0], tmp_val[1]}];
                        cout<<mid<<endl<<sjill<<' '<<sjane<<endl;
                        return 0;
                    }

                    rep(base, 0, 2) {
                        tmp_val[base] = ((tmp_val[base] - base_pow[base][mid - 1] * jane[i - mid + 1 + j]) % INF + INF) % INF;
                        tmp_val[base] = (tmp_val[base] * bases[base] + jane[i - mid + 1 + j]) % INF;
                    }
                }

                rep(j, 0, num_bases) hash_val[j] = ((hash_val[j] - base_pow[j][mid - 1] * jane[i - mid + 1]) % INF + INF) % INF;
            }
            reverse(all(jane));
        }
        possible.clear();
    }

    return 0;
}

Compilation message (stderr)

necklace.cpp: In function 'int main()':
necklace.cpp:8:42: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    8 | #define rep(i, a, b) for (int i = (a); i < (b); ++i)
      |                                          ^
necklace.cpp:52:9: note: in expansion of macro 'rep'
   52 |         rep(i, mid - 1, sz(jill)) {
      |         ^~~
necklace.cpp:8:42: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    8 | #define rep(i, a, b) for (int i = (a); i < (b); ++i)
      |                                          ^
necklace.cpp:63:13: note: in expansion of macro 'rep'
   63 |             rep(i, mid - 1, sz(jane)) {
      |             ^~~

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