Submission #2236563

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Source Code Expand

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

using VI = vector<int>;
using VVI = vector<VI>;
using PII = pair<int, int>;
using LL = long long;
using VL = vector<LL>;
using VVL = vector<VL>;
using PLL = pair<LL, LL>;
using VS = vector<string>;

#define ALL(a)  begin((a)),end((a))
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define EB emplace_back
#define MP make_pair
#define SZ(a) int((a).size())
#define SORT(c) sort(ALL((c)))
#define RSORT(c) sort(RALL((c)))
#define UNIQ(c) (c).erase(unique(ALL((c))), end((c)))

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)

#define FF first
#define SS second

#define DUMP(x) cout<<#x<<":"<<(x)<<endl
template<class S, class T>
istream& operator>>(istream& is, pair<S,T>& p){
  return is >> p.FF >> p.SS;
}
template<class T>
istream& operator>>(istream& is, vector<T>& xs){
  for(auto& x: xs)
	is >> x;
  return is;
}
template<class S, class T>
ostream& operator<<(ostream& os, const pair<S,T>& p){
  return os << p.FF << " " << p.SS;
}
template<class T>
ostream& operator<<(ostream& os, const vector<T>& xs){
  for(unsigned int i=0;i<xs.size();++i)
	os << (i?" ":"") << xs[i];
  return os;
}
template<class T>
void maxi(T& x, T y){
  if(x < y) x = y;
}
template<class T>
void mini(T& x, T y){
  if(x > y) x = y;
}


const double EPS = 1e-10;
const double PI  = acos(-1.0);
const LL MOD = 998244353;

LL powm(LL x, LL y){
  if(y <= 0) return 1ll;
  return powm(x*x%MOD, y/2) * (y%2?x:1ll) % MOD;
}

bool ison(PLL p1, PLL p2, PLL q){
  p1.FF -= q.FF;
  p1.SS -= q.SS;
  p2.FF -= q.FF;
  p2.SS -= q.SS;
  return p1.FF * p2.SS - p1.SS * p2.FF == 0;
}

int main(){
  cin.tie(0);
  ios_base::sync_with_stdio(false);

  LL N;
  cin >> N;
  vector<PLL> xs(N);
  cin >> xs;

  LL ans = (powm(2, N) + MOD - N - 1) % MOD;
  set<PLL> memo;
  REP(i,N) REP(j,i){
	VI ps;
	REP(k,N){
	  if(ison(xs[i], xs[j], xs[k])){
		ps.PB(k);
	  }
	}
	SORT(ps);
	auto p = MP(ps[0], ps[1]);
	if(memo.count(p)) continue;
	memo.insert(p);
	ans = (ans + MOD - (powm(2, SZ(ps)) - SZ(ps) - 1)) % MOD;
  }
  cout << ans << endl;

  return 0;
}

Submission Info

Judge Result