Submission #1124254

#	Time	Username	Problem	Language	Result	Execution time	Memory
1124254		adaawf	Group Photo (JOI21_ho_t3)	C++20	100 / 100	342 ms	576 KiB

Main

#include <iostream>
#include <vector>
using namespace std;
int n, t[5005], a[5005], c[5005], f[5005];
void upd(int x) {
    for (int i = x; i <= n; i += i & (-i)) {
        t[i]++;
    }
}
int sum(int x) {
    int res = 0;
    for (int i = x; i; i -= i & (-i)) {
        res += t[i];
    }
    return res;
}
int sum(int l, int r) {
    return sum(r) - sum(l - 1);
}
int main() {
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    cin >> n;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
        f[i] = 1e9;
    }
    for (int i = 0; i < n; i++) {
        vector<int> v;
        for (int j = 1; j <= n; j++) {
            if (a[j] > i) v.push_back(a[j]);
            c[j] = t[j] = 0;
        }
        for (int j = 0; j < v.size(); j++) c[v[j]] += j + 1;
        for (int j = i + 1; j <= n; j++) {
            c[j] += c[j - 1];
        }
        int d = 0;
        for (int j = i + 1; j <= n; j++) {
            int h = c[j] - (j - i + 1) * (j - i) / 2;
            d += sum(1, c[j] - c[j - 1] - 1);
            f[j] = min(f[j], f[i] + h + d);
            upd(c[j] - c[j - 1]);
        }
    }
    cout << f[n];
}

• Subtask 1: 5 / 5
• Subtask 2: 7 / 7
• Subtask 3: 32 / 32
• Subtask 4: 20 / 20
• Subtask 5: 36 / 36