Submission #936848

#	Time	Username	Problem	Language	Result	Execution time	Memory
936848		jcelin	Group Photo (JOI21_ho_t3)	C++14	100 / 100	526 ms	390708 KiB

Main

#include<bits/stdc++.h>

using namespace std;

typedef long long ll;

const int MAXN = 5007;
const ll INF = 1e18 + 7;
const int logo = 20;
const int off = 1 << logo;

ll inv[MAXN][MAXN], dp[MAXN], c[MAXN][MAXN];
//lesrig[y][x] - koliko brojeva je manje od y nadesno a oni su >= x
int lesrig[MAXN][MAXN], p[MAXN], a[MAXN], arr[MAXN];

ll vl(ll x){
	return (ll)x * (x - 1) / (ll)2;
}

void solve(){
	int n;
	cin >> n;
	for(int i=1; i<=n; i++) cin >> arr[i];

	
	for(int L=1; L<=n; L++){
		int cp = 1;
		for(int i=1; i<=n; i++) if(arr[i] >= L){
			a[cp] = arr[i];
			p[arr[i]] = cp++;
		}
		
		ll su1 = 0, su0 = 0;
		int id = 1;
		for(int R=L; R<=n; R++, id++){
			int cur = a[id];
			if(cur < R) su1 -= p[cur];
			else if(cur > R) su0 += p[cur];
			
			if(cur != R){
				if(p[R] <= id) su0 -= p[R];
				else su1 += p[R];
			}
			
			c[L][R] = su1 - su0;
		}
	}
	
	
	for(int i=0; i<=n; i++) p[i] = 0;
	for(int pos=n; pos; pos--){
		int cur = arr[pos];
		for(int x=1; x<=n; x++) lesrig[cur][x] = p[cur - 1] - p[x - 1];
		for(int i=cur; i<=n; i++) p[i]++;
	}
	
	
	for(int R=1; R<=n; R++){
		for(int L=1; L<R; L++){
			inv[L][R] = inv[L][R - 1] + lesrig[R][L];
		}
	}
	
	dp[0] = 0;
	for(int i=1; i<=n; i++) dp[i] = INF;
	for(int R=1; R<=n; R++){
		for(int L=0; L<R; L++){
			int len = R - L;
			dp[R] = min(dp[R], dp[L] + vl(len) - inv[L + 1][R] + c[L + 1][R]);
		}
	}
	cout << dp[n] << "\n";
}

int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);
	int tt = 1;
	//cin >> tt;
	while(tt--) solve();
	return 0;
}

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