Submission #1774757

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Source Code Expand

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int mod=998244353;
struct point{
	int x,y;
	point(){};
}p[210];

int n;
ll pw[210],ans;
point operator - (point a,point b){
	point ret;
	ret.x=a.x-b.x;
	ret.y=a.y-b.y;
	return ret;
}
ll cross(point a,point b){
	return a.x*b.y-a.y*b.x;
}
ll cross(point a,point b,point c){
	return abs(cross(a-c,b-c));
}
void solve(){
	cin>>n;pw[0]=1;
	for(int i=1;i<=n;++i){
		cin>>p[i].x>>p[i].y;
		pw[i]=pw[i-1]*2%mod;
	}
	ans=pw[n]-1-n;
	for(int i=1;i<=n;++i)
		for(int j=i+1;j<=n;++j){
			int cnt=0;
			for(int k=j+1;k<=n;++k)if(cross(p[i],p[j],p[k])<=0)++cnt;
			(ans+=mod-pw[cnt])%=mod;
		}
	printf("%lld\n",ans);
}
int main(){
	solve();
	
	return 0;
} 

Submission Info

Judge Result