poj 2954 Triangle
pick公式+gcd公式
1 #include<iostream> 2 #include<map> 3 #include<string> 4 #include<cstring> 5 #include<cstdio> 6 #include<cstdlib> 7 #include<cmath> 8 #include<queue> 9 #include<vector> 10 #include<algorithm> 11 #include<cmath> 12 using namespace std; 13 int gcd(int a,int b){ 14 if(b==0) return a; 15 int r; 16 while((r=a%b)){ 17 a=b; 18 b=r; 19 } 20 return b; 21 } 22 int main(){ 23 int x1,y1,x2,y2,x3,y3; 24 while(cin>>x1>>y1>>x2>>y2>>x3>>y3&&(x1||y1||x2||y2||x3||y3)){ 25 /*if(x1==0&&y1==0&&x2==0&&y2==0&&x3==0&&y3==0) 26 break;*/ 27 int area=fabs(((x1-x2)*(y1-y3)-(x1-x3)*(y1-y2))*1.0/2);//叉乘可能为负 28 //cout<<area<<endl; 29 int b=abs(gcd(x1-x2,y1-y2))+abs(gcd(x2-x3,y2-y3))+abs(gcd(x3-x1,y3-y1));//坐标平移，最大公约数+1就是边上的整点 30 //cout<<b<<endl; 31 int pick=area-b/2+1;//pick公式 32 cout<<pick<<endl; 33 } 34 return 0; 35 }
