Submission #974336

#	Time	Username	Problem	Language	Result	Execution time	Memory
974336		berr	Group Photo (JOI21_ho_t3)	C++17	100 / 100	656 ms	392828 KiB

Main

#include <bits/stdc++.h>
using namespace std; 
#define int long long
const int N=5005;
int ar[N][N], p[N][N],b[N], dp[N];
signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
   
    int n; cin >> n;

    vector<int> a(n);

    for(auto &i: a) cin >> i;

    for(int i=1; i<=n; i++) dp[i]=1e9;
    for(int i=0; i<n; i++){
        for(int l=0; l<i; l++){
            ar[a[i]][a[l]]++;
        }

        for(int l=n-1; l>=0; l--){
            ar[a[i]][l]+=ar[a[i]][l+1];
        }
    }

    //her i l için bir prefix sum
    for(int i=0; i<=n; i++){
        for(int l=0; l<=n; l++){
            p[i][l]=ar[l][i];
            if(l!=0) p[i][l]+=p[i][l-1];
        }
        b[i]+=ar[i][i];
        if(i!=0) b[i]+=b[i-1];
    }
    for(int i=1; i<=n; i++){
        int v=0;
        for(int l=i-1; l>=0; l--){
            int v=0;

            v+=p[i+1][i]-p[i+1][l];
            v+=p[l+1][i]-p[l+1][l];
            v-=b[i]-b[l];
      
            dp[i]=min(dp[i], dp[l]+v);
        }
       // cout<<"-----"<<dp[i]<<"\n";
    }

    cout<<dp[n];
}

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:37:13: warning: unused variable 'v' [-Wunused-variable]
   37 |         int v=0;
      |             ^

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