Submission #625118

#	Time	Username	Problem	Language	Result	Execution time	Memory
625118		Abrar_Al_Samit	Group Photo (JOI21_ho_t3)	C++17	64 / 100	5064 ms	58264 KiB

Main

#include<bits/stdc++.h>
using namespace std;

const int MX = 5004;

int n;
int a[MX];
int cost[MX][MX];
int st[MX*4];

void upd(int l, int r, int id, int val, int v) {
  if(l==r) {
    st[v] = val;
    return;
  }
  int mid = (l+r)/2;
  if(id<=mid) upd(l, mid, id, val, v*2);
  else upd(mid+1, r, id, val, v*2+1);
  st[v] = st[v*2]+st[v*2+1];
}
int query(int l, int r, int L, int R, int v) {
  if(l>=L && r<=R) return st[v];
  if(l>R || r<L) return 0;

  int mid = (l+r)/2;
  return query(l, mid, L, R, v*2) + query(mid+1, r, L, R, v*2+1);
}
int dp[MX];
int solve(int i) {
  if(i>n) return 0;
  int &ret = dp[i];
  if(ret!=-1) return ret;
  ret = INT_MAX;

  for(int j=i; j<=n; ++j) {
    ret = min(ret, solve(j+1)+cost[i][j]);
  }
  return ret;
}
int alt[MX];
void PlayGround() {
  cin>>n;
  for(int i=1; i<=n; ++i) {
    cin>>a[i];
    alt[a[i]] = i;
  }

  int inv[n+1] = {};
  for(int i=1; i<=n; ++i) {
    for(int j=alt[i]-1; j>0; --j) if(a[j]>i) {
      ++inv[i];
    }
  }

  for(int j=1; j<=n; ++j) {
    for(int i=1; i<=n; ++i) {
      upd(1, n, i, 0, 1);
    }
    for(int i=j; i>0; --i) {
      cost[i][j] = inv[i] - query(1, n, 1, alt[i], 1) + query(1, n, alt[i], n, 1);
      if(i!=j) cost[i][j] += cost[i+1][j];
      upd(1, n, alt[i], 1, 1);
    }
  }

  memset(dp, -1, sizeof dp);
  cout<<solve(1)<<'\n';
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  PlayGround();
  return 0;
}

• Subtask 1: 5 / 5
• Subtask 2: 7 / 7
• Subtask 3: 32 / 32
• Subtask 4: 20 / 20
• Subtask 5: 0 / 36