Submission #532748

#	Time	Username	Problem	Language	Result	Execution time	Memory
532748		Rafi22	Group Photo (JOI21_ho_t3)	C++14	100 / 100	288 ms	67652 KiB

Main

#include <bits/stdc++.h>

using namespace std;

#define endl '\n'
#define st first
#define nd second
#define pb push_back
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
#define ll long long
ll mod=1000000007;
int inf=1000000007;
ll infl=1000000000000000007;

int a[5007];
int ile[5007][5007];
int DP[5007];

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int n;
    cin>>n;
    for(int i=1;i<=n;i++) cin>>a[i];
    int inv=0;
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<i;j++)
        {
            if(a[j]>a[i])
            {
                inv++;
                ile[min(a[i],a[j])][max(a[i],a[j])]++;
            }
        }
    }
    for(int k=0;k<n;k++)
    {
        for(int i=1;i+k<=n;i++)
        {
            int j=i+k;
            ile[i][j]+=ile[i+1][j]+ile[i][j-1]-ile[i+1][j-1];
        }
    }
    for(int i=1;i<=n;i++)
    {
        DP[i]=inf;
        for(int j=i-1;j>=0;j--)
        {
            DP[i]=min(DP[i],DP[j]+(i-j)*(i-j-1)/2-2*ile[j+1][i]);
        }
    }
    cout<<inv+DP[n];
    return 0;
}

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