Submission #963429

#	Time	Username	Problem	Language	Result	Execution time	Memory
963429		12345678	Group Photo (JOI21_ho_t3)	C++17	100 / 100	348 ms	600 KiB

Main

#include <bits/stdc++.h>

using namespace std;

const int nx=5e3+5;

int dp[nx], n, x, idx[nx], cur;

struct fenwick
{
    int d[nx];
    void add(int i) {while (i<nx) d[i]++, i+=(i&-i);}
    int query(int i)
    {
        int res=0;
        while (i>0) res+=d[i], i-=(i&-i);
        return res;
    }
} f, l;

int main()
{
    cin.tie(NULL)->sync_with_stdio(false);
    cin>>n;
    for (int i=1; i<=n; i++) cin>>x, idx[x]=i;
    for (int i=1; i<=n; i++)
    {
        for (int j=1; j<=n; j++) l.d[j]=0;
        dp[i]=INT_MAX;
        cur=0;
        f.add(idx[i]);
        for (int j=i; j>0; j--)
        {
            cur+=f.query(nx-1)-f.query(idx[j]);
            //if (i==4) cout<<"here1 "<<j<<' '<<cur<<'\n';
            cur-=l.query(idx[j]);
            l.add(idx[j]);
            //if (i==4) cout<<"here2 "<<j<<' '<<cur<<'\n';
            dp[i]=min(dp[i], dp[j-1]+cur);
        }
        //cout<<"debug "<<i<<' '<<dp[i]<<'\n';
    }
    cout<<dp[n];
}

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