模板题。
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1 #include <iostream> 2 #include <cstring> 3 #include <cstdio> 4 #include <cstdlib> 5 #include <algorithm> 6 7 #define N 1000010 8 9 using namespace std; 10 11 struct PO 12 { 13 int x,y; 14 }p[N]; 15 16 char str[N]; 17 int n; 18 int dx[10]={0,-1,0,1,-1,0,1,-1,0,1}; 19 int dy[10]={0,-1,-1,-1,0,0,0,1,1,1}; 20 21 inline int cross(PO &a,PO &b,PO &c) 22 { 23 return (b.x-a.x)*(c.y-a.y)-(c.x-a.x)*(b.y-a.y); 24 } 25 26 inline long long llabs(long long x) 27 { 28 if(x>0) return x; 29 return -x; 30 } 31 32 inline void go() 33 { 34 scanf("%s",str+1); 35 n=strlen(str+1); 36 int a=0,b=0; 37 for(int i=1;i<=n;i++) 38 { 39 a+=dx[str[i]-'0']; 40 b+=dy[str[i]-'0']; 41 p[i].x=a; p[i].y=b; 42 } 43 long long area=0; 44 for(int i=1;i<n;i++) area+=(long long)cross(p[0],p[i],p[i+1]); 45 area=llabs(area); 46 if(area&1LL) printf("%lld.5\n",area>>1LL); 47 else printf("%lld\n",area>>1LL); 48 } 49 50 int main() 51 { 52 int cas; scanf("%d",&cas);getchar(); 53 while(cas--) go(); 54 return 0; 55 }