Submission #767802

#	Time	Username	Problem	Language	Result	Execution time	Memory
767802		dxz05	Ekoeko (COCI21_ekoeko)	C++17	110 / 110	15 ms	4416 KiB

Main

#include <bits/stdc++.h>

using namespace std;

#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define bpc(x) __builtin_popcount(x)
#define bpcll(x) __builtin_popcountll(x)
#define MP make_pair
#define BIT(x, i) (((x) >> (i)) & 1)
//#define endl '\n'

mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());

typedef long long ll;
const int MOD = 1e9 + 7;
const int N = 1e6 + 3e2;

ll calc(const string &s, const string &t){
    int n = (int) s.size();

    vector<queue<int>> q(26);
    for (int i = 0; i < n; i++) q[s[i] - 'a'].push(i);

    vector<int> a(n);
    for (int i = 0; i < n; i++){
        a[i] = q[t[i] - 'a'].front();
        q[t[i] - 'a'].pop();
    }

    ll inv = 0;

    vector<int> f(n + 1);
    for (int i = n - 1; i >= 0; i--){
        int x = a[i] + 1;

        while (x > 0) inv += f[x], x -= (-x) & x;

        x = a[i] + 1;
        while (x <= n) f[x]++, x += (-x) & x;
    }

    return inv;
}

void solve(){
    int n; string s;
    cin >> n >> s;

    vector<vector<int>> pos(26);
    for (int i = 0; i < 2 * n; i++){
        pos[s[i] - 'a'].push_back(i);
    }

    string a, b;
    vector<int> p(26, 0);

    for (int i = 0; i < 2 * n; i++){
        int x = s[i] - 'a';
        while (pos[x][p[x]] != i) p[x]++;

        if (p[x] * 2 < (int) pos[x].size()){
            a += s[i];
        } else {
            b += s[i];
        }
    }

    cout << calc(s, a + b) + calc(a, b) << endl;

}

int main(){
    clock_t startTime = clock();
    ios_base::sync_with_stdio(false);

#ifdef LOCAL
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif

    int test_cases = 1;
//    cin >> test_cases;

    for (int test = 1; test <= test_cases; test++){
        // cout << (solve() ? "YES" : "NO") << endl;
        solve();
    }

#ifdef LOCAL
    cerr << "Time: " << int((double) (clock() - startTime) / CLOCKS_PER_SEC * 1000) << " ms" << endl;
#endif

    return 0;
}

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:74:13: warning: unused variable 'startTime' [-Wunused-variable]
   74 |     clock_t startTime = clock();
      |             ^~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 20 / 20
• Subtask 3: 20 / 20
• Subtask 4: 20 / 20
• Subtask 5: 40 / 40