Submission #936540

#	TimeUTC-0	Username	Problem	Language	Result	Execution time	Memory
936540	2024-03-02 06:46:24	WongChun1234	Group Photo (JOI21_ho_t3)	C++14	100 / 100	589 ms	792 KiB

Main

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#include<bits/stdc++.h>
using namespace std;
const int N=5050;
int n,a[N],bit[2][N],pos[N],las[N][N],curr,dp[N];
void upd(int b,int id){
  for (;id<N;id+=id&-id) bit[b][id]++;
}
int qry(int b,int id){
  int ret=0;
  for (;id;id-=id&-id) ret+=bit[b][id];
  return ret;
}
int main(){
  cin>>n;
  for (int i=1;i<=n;i++){
    cin>>a[i];
    pos[a[i]]=i;
  }
  dp[0]=0;
  for (int i=1;i<=n;i++){
    for (int j=0;j<=n;j++) bit[0][j]=bit[1][j]=0;
    dp[i]=INT_MAX;
    for (int j=n;j>i;j--) upd(0,pos[j]);
    curr=0;
    for (int j=i;j;j--){
      curr+=qry(0,pos[j])+qry(1,n-pos[j]+1);
      dp[i]=min(dp[i],dp[j-1]+curr);
      //cout<<j<<"->"<<i<<" "<<curr<<"\n";
      upd(1,n-pos[j]+1);
    }
 
 
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• Subtask 1: 5 / 5
• Subtask 2: 7 / 7
• Subtask 3: 32 / 32
• Subtask 4: 20 / 20
• Subtask 5: 36 / 36