poj 2954 Triangle

#include <cstdio>#include <cstring>#include <iostream>#include <cstdlib>#include <ctime>#include <cmath>#include <algorithm>#include <set>#include <map>#include <queue>using namespace std;typedef double DB;inline int Gcd(int a,int b){return b==0? a:Gcd(b,a%b);}inline int ABS(int x){return x<0? (-x):x;}int main(){    int a1,a2,a3,b1,b2,b3,B=0,I=0;    double Area=0.0;    while(1){        scanf("%d%d%d%d%d%d",&a1,&b1,&a2,&b2,&a3,&b3);if(!a1 && !a2 && !a3 && !b1 && !b2 && !b3)break;Area=0.0; B=I=0;Area+=a1*b2-a2*b1; Area+=a2*b3-a3*b2; Area+=a3*b1-a1*b3;Area=fabs(Area/2.0);B+=Gcd(ABS(a2-a1),ABS(b2-b1));B+=Gcd(ABS(a3-a2),ABS(b3-b2));B+=Gcd(ABS(a1-a3),ABS(b1-b3));I=(int)Area+1-B/2;printf("%dn",I);}    return 0;}