Submission #1182651

#	Time	Username	Problem	Language	Result	Execution time	Memory
1182651		anteknne	Group Photo (JOI21_ho_t3)	C++20	44 / 100	5094 ms	328 KiB

Main

#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

typedef long long ll;
typedef long double ld;

#define pb push_back
#define pii pair<ll, ll>
#define pll pair<ll, ll>
#define st first
#define nd second
#define ordered_set tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>
#define debug false

const int MAXN = 5000;
int a[MAXN + 1];
int dp[MAXN + 1];
int pos[MAXN + 1];

int main () {
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    int n;
    cin >> n;

    for (int i = 1; i <= n; i ++) {
        cin >> a[i];
        pos[a[i]] = i;
    }

    for (int i = 1; i <= n; i ++) {
        dp[i] = INT_MAX;
    }
    dp[0] = 0;

    for (int i = 1; i <= n; i ++) {
        for (int j = 0; j < i; j ++) {
            int cnt = 0;
            for (int k = j + 1; k <= i; k ++) {
                for (int l = j + 1; l < k; l ++) {
                    cnt += (pos[k] > pos[l]);
                }
            }
            //cout << cnt << "\n";

            for (int k = 1; k <= j; k ++) {
                for (int l = j + 1; l <= i; l ++) {
                    cnt += (pos[k] > pos[l]);
                }
            }

            dp[i] = min(dp[i], dp[j] + cnt);

            //cout << cnt << "\n";
        }
    }

    cout << dp[n] << "\n";


    return 0;
}

• Subtask 1: 5 / 5
• Subtask 2: 7 / 7
• Subtask 3: 32 / 32
• Subtask 4: 0 / 20
• Subtask 5: 0 / 36