Submission #733831

#	Time	Username	Problem	Language	Result	Execution time	Memory
733831		epicci23	Naboj (COCI22_naboj)	C++17	110 / 110	311 ms	28020 KiB

naboj

#include "bits/stdc++.h"
#pragma optimize ("Bismillahirrahmanirrahim")
using namespace std;
#define pb push_back
#define ff first
#define ss second
#define endl "\n" 
#define int long long
#define double long double
#define sz(x) ((int)(x).size())
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define what_is(x) cerr << #x << " is " << x << endl;
//#define m (l+r)/2
constexpr int N=200005;
constexpr int MOD=1000000007;
constexpr int  INF2 = LLONG_MAX;
constexpr int INF=(int)1e18;
constexpr int LOG=30;
typedef pair<int,int> pii;
typedef tuple<int,int,int> tp;
typedef priority_queue<pii,vector<pii>,greater<pii>> min_pq;
typedef priority_queue<pii> max_pq;
typedef long long ll;
//to think//
/*
 * graph approach
 * dp
 * dividing the problem to smaller statements
 * finding the real constraint
 * sqrt decomposition
 * greedy approach
 * pigeonhole principle
 * rewriting the problem/equality 
 * bitwise approaches
 * binary search if monotonic
 * divide and conquer
 * combinatorics
 * inclusion - exclusion
 * think like bfs
*/



inline int in()
{
  int x;cin >> x;
  return x;
}

inline string in2()
{
  string x;cin >> x;
  return x;
}

vector<int> v[N];
bool ok=1;
int vis[N];

void dfs(int c)
{
  if(vis[c]==2) return;
  if(vis[c]==1)
  {
    ok=0;
    return;
  }
  vis[c]=1;
  for(int x:v[c]) dfs(x);
  vis[c]=2;
}

void solve()
{
  int n=in(),m=in();
  
  int freq[n+1];
  memset(freq,0,sizeof(freq));
  for(int i=1;i<=m;i++)
  {
    int a=in(),b=in();
    v[b].pb(a);
    freq[a]++;
  }

  for(int i=1;i<=n;i++) dfs(i);

  if(ok==0)
  {
    cout << -1 << endl;
    return;
  }

  vector<pii> ans;

  queue<int> q;
  for(int i=1;i<=n;i++) if(freq[i]==0) q.push(i);
  

  while(!q.empty())
  {
    int c=q.front();q.pop();
    ans.pb({c,1});
    for(int x:v[c])
    {
      freq[x]--;
      if(freq[x]==0) q.push(x);
    }
  }


  cout << sz(ans) << endl;
  for(auto x:ans) cout << x.ff << " " << x.ss << endl;
}

int32_t main(){
   

     cin.tie(0); ios::sync_with_stdio(0);
     cout << fixed <<  setprecision(15);
   
   int t=1;//cin>> t;
 
 for(int i=1;i<=t;i++)
 {
  //  cout << "Case #" << i << ": ";
    solve();
 }
 
 return 0;
}

Compilation message (stderr)

naboj.cpp:2: warning: ignoring '#pragma optimize ' [-Wunknown-pragmas]
    2 | #pragma optimize ("Bismillahirrahmanirrahim")
      |

• Subtask 1: 15 / 15
• Subtask 2: 25 / 25
• Subtask 3: 70 / 70