Submission #503321

#	Time	Username	Problem	Language	Result	Execution time	Memory
503321		Victor	Necklace (Subtask 1-3) (BOI19_necklace1)	C++17	25 / 85	528 ms	476 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 = 2147483647, MAXN = 3000;
const ll num_bases = 1, bases[] = {511, 31};
ll base_pow[num_bases][MAXN + 1], prefix_hash[3][num_bases][3001];

string jill, jane, revjane;

vll hash_val(int str, int pos, int len) {
    vll vals;
    rep(base, 0, num_bases) {
        ll rem = pos ? prefix_hash[str][base][pos - 1] : 0;
        rem = rem * base_pow[base][len] % INF;
        ll val = ((prefix_hash[str][base][pos + len - 1] - rem) % INF + INF) % INF;
        vals.pb(val);
    }
    return vals;
}

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 + 1) base_pow[i][j] = base_pow[i][j - 1] * bases[i] % INF;

    cin >> jill >> jane;
    trav(let, jill) let -= 'a';
    trav(let, jane) let -= 'a';
    revjane = jane;
    reverse(all(revjane));

    rep(i, 0, 3) {
        string str = jill;
        if (i == 1) str = jane;
        if (i == 2) str = revjane;
        rep(base, 0, num_bases) rep(j, 0, sz(str)) prefix_hash[i][base][j] = (str[j] + (j ? prefix_hash[i][base][j - 1] * bases[base] : 0)) % INF;
    }

    umap<ll, int> possible;
    int n = min(sz(jill), sz(jane));

    per(len, 1, n + 1) {
        rep(i, 0, sz(jill) - len + 1) {
            vll vals = hash_val(0, i, len);
            ll sum = 0, mult = 1;
            rep(base, 0, num_bases) {
                sum += vals[base] * mult;
                if (base + 1 != num_bases) mult *= INF;
            }
            possible.emplace(sum, i);
        }

        rep(j, 1, 3) {
            string str = jane;
            if (j == 2) str = revjane;

            rep(i, 0, sz(jane) - len + 1) {
                vll vals = hash_val(j, i, len);
                rep(k, 0, len) {
                    ll sum = 0, mult = 1;
                    rep(base, 0, num_bases) {
                        sum += vals[base] * mult;
                        if (base + 1 != num_bases) mult *= INF;
                    }

                    if (possible.count(sum)) {
                        int sjane = i;
                        if (j == 2) {
                            sjane = sz(jane) - sjane;
                            sjane -= len;
                        }
                        cout << len << endl
                             << possible[sum] << ' ' << sjane << endl;
                        return 0;
                    }

                    rep(base, 0, num_bases) {
                        vals[base] = ((vals[base] - base_pow[base][len - 1] * str[i + k]) % INF + INF) % INF;
                        vals[base] = (vals[base] * bases[base] + str[i + k]) % INF;
                    }
                }
            }
        }
        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:65:33: note: in expansion of macro 'rep'
   65 |         rep(base, 0, num_bases) rep(j, 0, sz(str)) prefix_hash[i][base][j] = (str[j] + (j ? prefix_hash[i][base][j - 1] * bases[base] : 0)) % INF;
      |                                 ^~~
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:72:9: note: in expansion of macro 'rep'
   72 |         rep(i, 0, sz(jill) - len + 1) {
      |         ^~~
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:86:13: note: in expansion of macro 'rep'
   86 |             rep(i, 0, sz(jane) - len + 1) {
      |             ^~~

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