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## 跑了32MS，有兴趣的看看

Posted by gtzygtzy at 2009-09-18 20:30:52 on Problem 1654
In Reply To:这题怎么节省时间，我按照经典的叉积方法实现，却用了500多ms,请问15ms的是怎么搞的？ Posted by:liyineng at 2006-07-30 12:14:45
```> 这题怎么节省时间，我按照经典的叉积方法实现，却用了500多ms,请问15ms的是怎么搞的？
#include<iostream>
using namespace std;
char in[1000010];
struct point
{
int x,y;
}pre,now;
int cx[]={0,-1,-1,-1,0,0,0,1,1,1};
int cy[]={0,-1,0,1,-1,0,1,-1,0,1};
int main()
{
int test,i;
__int64 re;
scanf("%d",&test);
while(test--)
{
scanf("%s",in);
i=0;
pre.x=0;pre.y=0;
now.x=0;now.y=0;
re=0;
while(in[i]!='5')
{
if(i>0 && in[i]!=in[i-1])
{
re+=pre.x*now.y-pre.y*now.x;
pre=now;
now.x=now.x+cx[in[i]-'0'];
now.y=now.y+cy[in[i]-'0'];
}
else
{
now.x=now.x+cx[in[i]-'0'];
now.y=now.y+cy[in[i]-'0'];
}
i++;
}
pre.x=0;pre.y=0;
re+=pre.x*now.y-pre.y*now.x;
if(re<0) re=-re;
if(re%2) printf("%I64d.5\n",re/2);
else printf("%I64d\n",re/2);
}
return 0;
}```

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