Submission #733586

#	Time	Username	Problem	Language	Result	Execution time	Memory
733586		stevancv	Group Photo (JOI21_ho_t3)	C++14	100 / 100	130 ms	134416 KiB

Main

#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define sp ' '
#define en '\n'
#define smin(a, b) a = min(a, b)
#define smax(a, b) a = max(a, b)
using namespace std;
const int N = 5e3 + 2;
const int inf = 2e9 + 2;
int dp[N][N], pref[N][N], p[N], ip[N], mn[N];
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int n; cin >> n;
    for (int i = 1; i <= n; i++) {
        cin >> p[i];
        ip[p[i]] = i;
    }
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j < i; j++) {
            if (ip[j] > ip[i]) pref[i][j] = 1;
            pref[i][j] += pref[i][j - 1];
        }
    }
    for (int i = 1; i <= n; i++) {
        mn[i] = inf;
        for (int j = 1; j <= i; j++) dp[i][j] = inf;
    }
    for (int i = 1; i <= n; i++) {
        dp[i][1] = mn[i] = mn[i - 1] + pref[i][i - 1];
        for (int j = 2; j <= i; j++) {
            dp[i][j] = dp[i - 1][j - 1] + 2 * pref[i][i - j] - pref[i][i - 1] + j - 1;
            smin(mn[i], dp[i][j]);
        }
    }
    cout << mn[n] << en;
    return 0;
}

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