Submission #936540

#	Time	Username	Problem	Language	Result	Execution time	Memory
936540		WongChun1234	Group Photo (JOI21_ho_t3)	C++14	100 / 100	589 ms	792 KiB

Main

#include<bits/stdc++.h>
using namespace std;
const int N=5050;
int n,a[N],bit[2][N],pos[N],las[N][N],curr,dp[N];
void upd(int b,int id){
	for (;id<N;id+=id&-id) bit[b][id]++;
}
int qry(int b,int id){
	int ret=0;
	for (;id;id-=id&-id) ret+=bit[b][id];
	return ret;
}
int main(){
	cin>>n;
	for (int i=1;i<=n;i++){
		cin>>a[i];
		pos[a[i]]=i;
	}
	dp[0]=0;
	for (int i=1;i<=n;i++){
		for (int j=0;j<=n;j++) bit[0][j]=bit[1][j]=0;
		dp[i]=INT_MAX;
		for (int j=n;j>i;j--) upd(0,pos[j]);
		curr=0;
		for (int j=i;j;j--){
			curr+=qry(0,pos[j])+qry(1,n-pos[j]+1);
			dp[i]=min(dp[i],dp[j-1]+curr);
			//cout<<j<<"->"<<i<<" "<<curr<<"\n";
			upd(1,n-pos[j]+1);
		}
		//cout<<i<<": "<<dp[i]<<"\n";
	}
	cout<<dp[n]<<"\n";
}

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