Submission #917682

#	Time	Username	Problem	Language	Result	Execution time	Memory
917682		406	Group Photo (JOI21_ho_t3)	C++17	100 / 100	138 ms	77692 KiB

Main

#include <bits/stdc++.h>
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)

using namespace std;
using ar = array<int, 2>;

const int64_t INF = 1ll << 30;
const int N = 5000 + 50;
int dp[N], sum[N][N], cnt[N], loc[N], n, a[N];

signed main() {
        ios::sync_with_stdio(false);
        cin.tie(nullptr); 
        cin >> n;
        FOR(i, 0, n) {
                cin >> a[i];
                --a[i];
                loc[a[i]] = i;
        }
        FOR(q, 0, n) FOR(i, q + 1, n) sum[q][i] = (loc[q] > loc[i]) + sum[q][i - 1];
        fill(dp, dp + N, INF);
        dp[0] = 0;
        FOR(i, 1, n) {
                int ct = 0;
                for (int j = n - 1; j >= 0; --j) if (a[j] <= i)
                        cnt[a[j]] = ct++;
                int s = 0;
                for (int q = i; q >= 0; --q) {
                        s -= sum[q][i];
                        s += cnt[q];
                        dp[i] = min(dp[i], (q ? dp[q - 1] : 0) + s);
                }
        }
        cout << dp[n - 1] << '\n';
        return 0;
}

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