Submission #372320

#	Time	Username	Problem	Language	Result	Execution time	Memory
372320		errorgorn	Group Photo (JOI21_ho_t3)	C++17	100 / 100	1031 ms	620 KiB

Main

//雪花飄飄北風嘯嘯
//天地一片蒼茫

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>
using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
#define ll long long
#define ii pair<ll,ll>
#define iii pair<ii,ll>
#define fi first
#define se second
#define endl '\n'
#define debug(x) cout << #x << " is " << x << endl

#define pub push_back
#define pob pop_back
#define puf push_front
#define pof pop_front
#define lb lower_bound
#define up upper_bound

#define rep(x,start,end) for(auto x=(start)-((start)>(end));x!=(end)-((start)>(end));((start)<(end)?x++:x--))
#define all(x) (x).begin(),(x).end()
#define sz(x) (int)(x).size()

#define indexed_set tree<ll,null_type,less<ll>,rb_tree_tag,tree_order_statistics_node_update>
//change less to less_equal for non distinct pbds, but erase will bug

mt19937 rng(chrono::system_clock::now().time_since_epoch().count());

struct FEN{
	int fen[5005];
	
	FEN(){
		memset(fen,0,sizeof(fen));
	}
	
	void update(int i,int k){
		while (i<5005){
			fen[i]+=k;
			i+=i&-i;
		}
	}
	
	int query(int i){
		int res=0;
		while (i){
			res+=fen[i];
			i-=i&-i;
		}
		return res;
	}
	
	int query(int i,int j){
		return query(j)-query(i-1);
	}
} hi,lo;

int n;
int arr[5005];
int pos[5005];
ll dp[5005];

int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin.exceptions(ios::badbit | ios::failbit);
	
	cin>>n;
	rep(x,1,n+1) cin>>arr[x];
	rep(x,1,n+1) pos[arr[x]]=x;
	
	memset(dp,63,sizeof(dp));
	
	dp[0]=0;
	rep(x,0,n){
		hi=FEN();
		lo=FEN();
		
		rep(y,x+1,n+1) hi.update(pos[y],1);
		
		ll curr=dp[x];
		rep(y,x+1,n+1){
			curr+=hi.query(1,pos[y]-1);
			curr+=lo.query(1,pos[y]-1);
			curr-=lo.query(pos[y]+1,5004);
			
			//cout<<x<<" "<<y<<" "<<curr<<endl;
			dp[y]=min(dp[y],curr);
			
			hi.update(pos[y],-1);
			lo.update(pos[y],1);
		}
	}
	
	//rep(x,0,n+1) cout<<dp[x]<<" "; cout<<endl;
	cout<<dp[n]<<endl;
}

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