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Submission #513868

# Submission time Handle Problem Language Result Execution time Memory
513868 2022-01-17T20:15:43 Z czhang2718 Monochrome Points (JOI20_monochrome) C++17
0 / 100
 1 ms 332 KB 
#include "bits/stdc++.h"
using namespace std;

const int N=400001;

int n;
string s;
int r[N], l[N];
int sum[4*N];

void upd(int i, int x, int lx, int rx){
  sum[x]++;
  if(rx-lx==1) return;
  int m=(lx+rx)/2;
  if(i<m) upd(i, 2*x+1, lx, m);
  else upd(i, 2*x+2, m, rx);
}

void upd(int i) { upd(i, 0, 0, 2*n+1); }

int get_sum(int l, int r, int x, int lx, int rx){
  if(lx>=r || rx<=l) return 0;
  if(lx>=l && rx<=r) return sum[x];
  int m=(lx+rx)/2;
  return get_sum(l, r, 2*x+1, lx, m)+get_sum(l, r, 2*x+2, m, rx);
}

int get_sum(int l, int r) { 
  if(r<=l) return 0;
  return get_sum(l, r, 0, 0, 2*n+1); 
}

int main(){
  cin.tie(0)->sync_with_stdio(0);

  cin >> n >> s;

  long long ans2=0;
  for(int t=0; t<n; t++){
    vector<int> white, black;
    for(int i=n; i<2*n; i++){
      if(s[i]=='W') white.push_back(i+1);
      else black.push_back(i+1);
    }
    int j=0, k=0;
    for(int i=0; i<n; i++){
      if(s[i]=='B') {
        l[white[j]]=i+1, r[i+1]=white[j];
        j++;
      }
      else{
        l[black[k]]=i+1, r[i+1]=black[k];
        k++;
      }
    }
    // for(int i=0; i<n; i++){
    //   cout << "r[" << i+1 << "] = " << r[i+1] << "\n";
    // }

    long long ans=0;
    for(int i=1; i<=2*n; i++){
      if(r[i]) continue;
      ans+=get_sum(l[i]+1, i);
      upd(l[i]);
    }
    ans2=max(ans2, (long long)n*(n-1)/2-ans);

    s+=s[0];
    s.erase(s.begin());
  }
  cout << ans2;
}

Subtask #1
0.0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 320 KB Output is correct
2 Correct 1 ms 324 KB Output is correct
3 Correct 0 ms 332 KB Output is correct
4 Correct 0 ms 324 KB Output is correct
5 Incorrect 0 ms 332 KB Output isn't correct
6 Halted 0 ms 0 KB -

Subtask #2
0.0 / 21.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 320 KB Output is correct
2 Correct 1 ms 324 KB Output is correct
3 Correct 0 ms 332 KB Output is correct
4 Correct 0 ms 324 KB Output is correct
5 Incorrect 0 ms 332 KB Output isn't correct
6 Halted 0 ms 0 KB -

Subtask #3
0.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 320 KB Output is correct
2 Correct 1 ms 324 KB Output is correct
3 Correct 0 ms 332 KB Output is correct
4 Correct 0 ms 324 KB Output is correct
5 Incorrect 0 ms 332 KB Output isn't correct
6 Halted 0 ms 0 KB -

Subtask #4
0.0 / 65.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 320 KB Output is correct
2 Correct 1 ms 324 KB Output is correct
3 Correct 0 ms 332 KB Output is correct
4 Correct 0 ms 324 KB Output is correct
5 Incorrect 0 ms 332 KB Output isn't correct
6 Halted 0 ms 0 KB -