Submission #3587

#	Time	Username	Problem	Language	Result	Execution time	Memory
3587		waps12b	Divide into triangle (kriii1_D)	C++98	0 / 1	0 ms	1096 KiB

D

#include<cstdio>
#include<vector>
#include<algorithm>
#include<string>
using namespace std;
#define ll long long 
#define ccw(a,b,c) ( (a.x*b.y + b.x*c.y + c.x * a.y ) - ( a.y*b.x + b.y*c.x + c.y * a.x) )
struct pt{
	ll x,y;
	int pos;
	pt(){}
	pt(ll x,ll y){
		this->x=x;
		this->y=y;
	}
};
pt v[300];
pt STD;
bool compare(pt a,pt b){
	return (ccw(STD,a,b) < 0);
}



int main(){
	int n;scanf("%d",&n);
	n*=3;
	for(int i=0;i<n;i++){
		ll x, y;scanf("%lld %lld",&x,&y);
		v[i] = pt(x,y);
		v[i].pos = i+1;
	}
	STD = pt(-1e9,-1e9);
	sort(v,v+n,compare);
	for(int i=0;i<n;i+=3)
		printf("%d %d %d\n",v[i].pos,v[i+1].pos,v[i+2].pos);
	return 0;
}

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