poj1654 Area

#include<cmath>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
typedef long long ll;
struct Point
{
    ll x,y;
    Point(){}
    Point(ll x,ll y):x(x),y(y){}
    Point operator + (const Point&a)const{return Point(x+a.x,y+a.y);}
    Point operator - (const Point&a)const{return Point(x-a.x,y-a.y);}
    ll operator ^ (const Point&a)const{return x*a.y-y*a.x;}
}p[10];
typedef Point Vector;
int T;
char ch[1000050];
void init()
{
    p[1] = Point(-1,-1),p[2] = Point(0,-1),p[3] = Point(1,-1),p[4] = Point(-1,0);
    p[6] = Point(1,0),p[7] = Point(-1,1),p[8] = Point(0,1),p[9] = Point(1,1);
}
void work()
{
    scanf("%s",ch+1);
    Point s0(0,0),s1(0,0),s2(0,0);
    int len = strlen(ch+1);
    long long ans = 0;
    for(int i=1;i<len;i++)
    {
        s1 = s2,s2 = s2+p[ch[i]-‘0‘];
        ans+=((s1-s0)^(s2-s0));
    }
    if(ans<0)ans=-ans;
    if(ans&1)
    {
        printf("%lld.5\n",ans/2);
    }else
    {
        printf("%lld\n",ans/2);
    }
}
int main()
{
    scanf("%d",&T);init();
    while(T--)work();
    return 0;
}