Submission #415242

#	Time	Username	Problem	Language	Result	Execution time	Memory
415242		keta_tsimakuridze	Group Photo (JOI21_ho_t3)	C++14	100 / 100	842 ms	509324 KiB

Main

#include<bits/stdc++.h>
#define f first
#define int long long
#define s second
using namespace std;
const int N=5005,mod=1e9+7,Inf=1e9;
int t,ind[N],dp[N],inv[N][N],p[N][N],n,a[N],I[N][N];
string s;
 main(){
	// t=1;
	cin >> n;
	for(int i=1;i<=n;i++){
		cin>>a[i];
		ind[a[i]] = i;
	}
	for(int i=1;i<=n;i++){
		for(int j=1;j<=n;j++) {
			inv[i][j] = inv[i][j-1] + (ind[j]>ind[i]);
			p[i][j] = p[i-1][j] + inv[i][j];
		}	
	}    
	for(int i=1;i<=n;i++) {
		dp[i] = Inf;
		for(int j=i;j<=n;j++){
			I[i][j] = I[i][j-1] + (j-i) - (inv[j][j] - inv[j][i-1]); 
			
		}
	}
	for(int i=1;i<=n;i++) {
		for(int j=i;j<=n;j++) {
			//   i-1>>>>>1  j>>>>>i
			dp[j] = min(dp[j],dp[i-1] + (p[j][i-1] - p[i-1][i-1]) + I[i][j] );
		}
	}
	cout<<dp[n];
}

Compilation message (stderr)

Main.cpp:9:2: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
    9 |  main(){
      |  ^~~~

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