Submission #667288

#	Time	Username	Problem	Language	Result	Execution time	Memory
667288		Darren0724	Group Photo (JOI21_ho_t3)	C++17	100 / 100	891 ms	196488 KiB

Main

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define all(x) x.begin(),x.end()
#define pii pair<int,int>
#define mp make_pair
const int INF=1e18;
const int mod=1e9+7;
struct BIT{
    vector<int> v;
    int n;
    BIT(int n1){
        n=n1;
        v.resize(n+1);
    }
    void add(int p,int x){
        for(int i=p;i<=n;i+=i&(-i)){
            v[i]+=x;
        }
    }
    int ask(int p){
        int ans=0;
        for(int i=p;i>0;i-=i&(-i)){
            ans+=v[i];
        }
        return ans;
    }
};
signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    int n;cin>>n;
    vector<int> pos(n+1);
    vector<vector<int>> cnt(n+2,vector<int>(n+2));
    for(int i=1;i<=n;i++){
        int k;cin>>k;
        pos[k]=i;
    }
    for(int j=1;j<=n;j++){
        BIT bit(n);
        for(int i=j+1;i<=n;i++){
            bit.add(pos[i],1);
        }
        for(int i=j;i>=1;i--){
            cnt[i][j]=cnt[i+1][j]+bit.ask(pos[i]-1);
        }
    }
    for(int i=1;i<=n;i++){
        BIT bit(n);
        int tmp=0;
        for(int j=i;j<=n;j++){
            tmp+=bit.ask(pos[j]);
            cnt[i][j]+=tmp;
            bit.add(pos[j],1);
        }
    }
    vector<int> dp(n+1,INF);
    dp[0]=0;
    for(int i=1;i<=n;i++){
        for(int j=0;j<i;j++){
            dp[i]=min(dp[i],dp[j]+cnt[j+1][i]);
        }
    }
    cout<<dp[n]<<endl;



    return 0;
}

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