Submission #937894

#	Time	Username	Problem	Language	Result	Execution time	Memory
937894		zwezdinv	Group Photo (JOI21_ho_t3)	C++17	100 / 100	369 ms	98644 KiB

Main

#include <bits/stdc++.h>

int main() {
        std::cin.tie(nullptr)->sync_with_stdio(false);

        int n;
        std::cin >> n;
        std::vector<int> h(n);
        for (auto& i : h) std::cin >> i;
        std::vector<int> pos(n);
        for (int i = 0; i < n; ++i) pos[h[i] - 1] = i;
        std::vector<std::vector<int>> pref(n + 1, std::vector<int>(n + 1));
        for (int i = 0; i < n; ++i) {
                pref[i + 1] = pref[i];
                for (int j = 0; j <= n; ++j) {
                        if (h[i] <= j) pref[i + 1][j]++;
                }
        }
        std::vector<int> dp(n + 1, 1e9);
        dp[0] = 0;
        for (int i = 0; i < n; ++i) {
                int cur = dp[i];
                for (int j = i; j < n; ++j) {
                        int k = pos[j];
                        int add = k - i;
                        add += pref[n][j] - pref[k][j];
                        add -= 2 * ((pref[n][j] - pref[n][i]) - (pref[k][j] - pref[k][i]));
                        cur += add;
                        dp[j + 1] = std::min(dp[j + 1], cur);
                }
        }
        std::cout << dp[n];
}

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