Submission #380859

#	Time	Username	Problem	Language	Result	Execution time	Memory
380859		Bill_00	Group Photo (JOI21_ho_t3)	C++14	100 / 100	508 ms	165484 KiB

Main

#include <bits/stdc++.h>
#define ll long long
#define N 5002
#define INF 1000000000
using namespace std;
int a[N],dp[N],pos[N];
int p[N][N],x[N][N];
int main(){
	ios_base::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++){
		for(int j=n;j>=1;j--){
			if(a[j]<=i){
				x[i][j]=x[i][j+1]+1;
			}
			else x[i][j]=x[i][j+1];
		}
	}
	for(int i=1;i<=n;i++){
		for(int j=1;j<=(n-i+1);j++){
			int pp=pos[i+j-1];
			int u=x[i-1][pp];
			p[i][j]=p[i][j-1]+pp+u-i-(x[i+j-1][pp+1]-x[i-1][pp]);
		}
	}
	for(int i=1;i<=n;i++){
		dp[i]=INF;
	}
	for(int i=1;i<=n;i++){
		for(int j=0;j<i;j++){
			dp[i]=min(dp[j]+p[j+1][i-j],dp[i]);
		}
	}
	cout << dp[n];

}

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