Submission #1086235

#	Time	Username	Problem	Language	Result	Execution time	Memory
1086235		vako_p	Group Photo (JOI21_ho_t3)	C++14	100 / 100	255 ms	196696 KiB

Main

#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back

const int mxN = 5005; 
ll n,a[mxN],cnt[mxN][mxN],dp[mxN],idx[mxN];
 
int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cin>>n;
    for(int i = 1; i <= n; i++){
        cin >> a[i];
        idx[a[i]] = i;
    }
    for(int i = 1; i <= n; i++){
    	for(int j = 1; j <= n; j++){
    		cnt[i][j] = cnt[i - 1][j] + (a[i] >= j);
		}
	}
	for(int i = 1; i <= n; i++){
		ll sum = 0;
		dp[i] = 1e18;
		for(int j = i; j > 0; j--){
			sum += (i - j) + cnt[idx[j]][i + 1];
 			sum -= cnt[idx[j]][j + 1] - cnt[idx[j]][i + 1];
			dp[i] = min(dp[i], dp[j - 1] + sum);
		}
	}
	cout << dp[n];
}

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