Submission #740329

#	Time	Username	Problem	Language	Result	Execution time	Memory
740329		stevancv	Boarding Passes (BOI22_passes)	C++14	100 / 100	240 ms	23436 KiB

passes

#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define sp ' '
#define en '\n'
#define smin(a, b) a = min(a, b)
#define smax(a, b) a = max(a, b)
using namespace std;
const int N = 1e5 + 2;
const int M = 15;
const int K = 1 << M;
const ll linf = 1e18;
vector<ll> pref[M][M], suff[M][M];
vector<int> pos[M];
ll dp[K];
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    string s; cin >> s;
    int n = s.size();
    for (int i = 0; i < n; i++) pos[s[i] - 'A'].push_back(i);
    for (int i = 0; i < M; i++) {
        for (int j = 0; j < M; j++) {
            if (i == j) continue;
            pref[i][j].resize(pos[i].size());
            int jj = 0;
            for (int ii = 0; ii < pos[i].size(); ii++) {
                while (jj < pos[j].size() && pos[j][jj] < pos[i][ii]) jj += 1;
                pref[i][j][ii] = 2 * jj;
                if (ii > 0) pref[i][j][ii] += pref[i][j][ii - 1];
            }
        }
    }
    for (int i = 0; i < M; i++) {
        for (int j = 0; j < M; j++) {
            if (i == j) continue;
            suff[i][j].resize(pos[i].size());
            int jj = pos[j].size() - 1;
            for (int ii = pos[i].size() - 1; ii >= 0; ii--) {
                while (jj >= 0 && pos[j][jj] > pos[i][ii]) jj -= 1;
                suff[i][j][ii] = 2 * (pos[j].size() - jj - 1);
                if (ii < pos[i].size() - 1) suff[i][j][ii] += suff[i][j][ii + 1];
            }
        }
    }
    for (int mask = 1; mask < K; mask++) {
        dp[mask] = linf;
        for (int i = 0; i < M; i++) {
            if (!((1 << i) & mask)) continue;
            int uk = pos[i].size();
            auto F = [&] (ll kol) {
                ll ans = kol * (kol - 1) / 2;
                ans += (uk - kol) * (uk - kol - 1) / 2;
                for (int j = 0; j < M; j++) {
                    if (i != j && ((1 << j) & mask)) {
                        if (kol > 0) ans += pref[i][j][kol - 1];
                        if (kol < uk) ans += suff[i][j][kol];
                    }
                }
                return ans;
            };
            int l = 0, r = uk - 1, gde = uk;
            while (l <= r) {
                int mid = l + r >> 1;
                if (F(mid) < F(mid + 1)) {
                    gde = mid;
                    r = mid - 1;
                }
                else l = mid + 1;
            }
            smin(dp[mask], dp[mask ^ (1 << i)] + F(gde));
        }
    }
    cout << dp[K - 1] / 2;
    if (dp[K - 1] % 2 == 1) cout << ".5" << en;
    return 0;
}

Compilation message (stderr)

passes.cpp: In function 'int main()':
passes.cpp:28:33: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   28 |             for (int ii = 0; ii < pos[i].size(); ii++) {
      |                              ~~~^~~~~~~~~~~~~~~
passes.cpp:29:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   29 |                 while (jj < pos[j].size() && pos[j][jj] < pos[i][ii]) jj += 1;
      |                        ~~~^~~~~~~~~~~~~~~
passes.cpp:43:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   43 |                 if (ii < pos[i].size() - 1) suff[i][j][ii] += suff[i][j][ii + 1];
      |                     ~~~^~~~~~~~~~~~~~~~~~~
passes.cpp:65:29: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   65 |                 int mid = l + r >> 1;
      |                           ~~^~~

• Subtask 1: 5 / 5
• Subtask 2: 25 / 25
• Subtask 3: 30 / 30
• Subtask 4: 40 / 40