Submission #949883

#	Time	Username	Problem	Language	Result	Execution time	Memory
949883		fuad27	Alternating Current (BOI18_alternating)	C++17	33 / 100	3024 ms	2396 KiB

alternating

#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3")
mt19937 rng(chrono::steady_clock().now().time_since_epoch().count());
long double P(int old, int nw, long double temp) {
  if(nw < old)return 1.0;
  return exp((old-nw)/temp);

}
vector<int> mask;
vector<pair<int,int>> a;
int n, m;
int eval() {
  int cnt1[n+1], cnt2[n+1];
  memset(cnt1, 0, sizeof cnt1);
  memset(cnt2, 0, sizeof cnt2);
  for(int i = 0;i<m;i++) {
    if(mask[i]) {
      if(a[i].second>=a[i].first) {
        cnt1[a[i].first]++;
        cnt1[a[i].second+1]--;
      }
      else {
        cnt1[a[i].first]++;
        cnt1[0]++;
        cnt1[a[i].second+1]--;
      }
    }
    else {
      if(a[i].second>=a[i].first) {
        cnt2[a[i].first]++;
        cnt2[a[i].second+1]--;
      }
      else {
        cnt2[a[i].first]++;
        cnt2[0]++;
        cnt2[a[i].second+1]--;
      }
    }
  }
  for(int i = 1;i<=n;i++) {
    cnt1[i]+=cnt1[i-1];
    cnt2[i]+=cnt2[i-1];
  }
  int cc=0;
  for(int i = 0;i<n;i++) {
    if(cnt1[i]<=0)cc++;
    if(cnt2[i]<=0)cc++;
  }
  return cc;
}
int main () {
  cin.tie(0)->sync_with_stdio(0);
  cin >> n >> m;
  auto start=clock();
  mask.resize(m);
  a.resize(m);
  for(int i = 0;i<m;i++){
    cin >> a[i].first >> a[i].second;
    a[i].first--;
    a[i].second--;
  }
  while((long double)(clock()-start)/CLOCKS_PER_SEC < 2.0) {
    long double temp = 1000;
    for(int i = 0;i<m;i++)mask[i]=rng()%2;
    int old = eval();
    for(int i = 0;i<10000;i++) {
      int c = rng()%m;
      mask[c]^=1;
      int nw = eval();
      if(nw==0) {
        for(int i:mask)cout << i;
        cout << "\n";
        return 0;
      }
      long double rn = (long double)(rng()%1000)/1000;
      if(P(old, nw, temp)>rn) {
        old=nw;
      }
      else {
        mask[c]^=1;
      }
      temp*=0.95;
    }
//    cerr << fixed << setprecision(5) << (long double)temp << endl;
  }
  cout << "impossible\n";
}

• Subtask 1: 13 / 13
• Subtask 2: 20 / 20
• Subtask 3: 0 / 22
• Subtask 4: 0 / 19
• Subtask 5: 0 / 26