Submission #377272

#	Time	Username	Problem	Language	Result	Execution time	Memory
377272		YJU	Group Photo (JOI21_ho_t3)	C++14	100 / 100	1244 ms	620 KiB

Main

#include<bits/stdc++.h>
#pragma GCC optimize("unroll-loops,no-stack-protector,Ofast")
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> pll;
const ll MOD=1e9+7;
const ll MOD2=998244353;
const ll N=5e3+5;
const ld pi=acos(-1);
const ll INF=(1LL<<60);
#define SQ(i) ((i)*(i))
#define REP(i,n) for(ll i=0;i<n;i++)
#define REP1(i,n) for(ll i=1;i<=n;i++)
#define pb push_back
#define mp make_pair
#define X first
#define Y second
#define setp setprecision
#define lwb lower_bound
#define SZ(_a) (ll)_a.size()

ll bit[N];

ll n,x,h[N],dp[N];

void add(ll id,ll del){
	for(int i=id;i<N;i+=(i&-i)){
		bit[i]+=del;
	}
}

ll query(ll id){
	ll tmp=0;
	for(int i=id;i;i-=(i&-i)){
		tmp+=bit[i];
	}
	return tmp;
}

int main(){
	ios_base::sync_with_stdio(0);cin.tie(0);
	cin>>n;
	REP1(i,n)cin>>x,h[x]=i;
	REP1(i,n)dp[i]=INF;
	REP(i,n){
		//memset(bit,0,sizeof(bit));
		for(int j=i+1;j<=n;j++){add(h[j],1);}
		ll sum=0;
		for(int j=i+1;j<=n;j++){
			sum+=query(h[j])-1;
			add(1,-1);add(h[j],1);
			dp[j]=min(dp[j],dp[i]+sum);
		}
		for(int j=i+1;j<=n;j++)add(1,1),add(h[j],-2);
	} 
	cout<<dp[n]<<"\n";
	return 0;
}

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