537 - Artificial Intelligence?

一开始没看清题（uva的题目就是坑爹） WA了好多次。原因：k，m，M是通用单位，PUI都可以用。

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cctype>
using namespace std;
double readnum(char *a,int begin,int *end)
{
  int i=begin,j=0;
  char tmp[1001];
  double num;
  memset(tmp, '\0', 1001);
  while(!isalpha(a[i]))
  {
    tmp[j]=a[i];
    i++;j++;
  }
  tmp[j]='\0';
  *end=i;
  sscanf(tmp,"%lf",&num);
  //printf("a: %stmp:%s num:%lf\n",a,tmp,num);
  if(a[i]=='m') num=num/1000.0;
  else if(a[i]=='k') num=num*1000.0;
  else if(a[i]=='M') num=num*1000000.0;
  return num ;
}
int main()
{
  int k;
  scanf("%d",&k);fgetc(stdin);//吃一个回车 
  for(int i=1;i<=k;i++)
  {
      double P=0,U=0,I=0;
      char problem[1001],concept;
      char prefix;
      double realnum;
    int end;
      fgets(problem,1000,stdin);
      for(int j=0;j<strlen(problem);j++)
      {
        if(problem[j]=='=') 
        {
          concept=problem[j-1];
          realnum=readnum(problem,j+1,&end);
          prefix=problem[end];
          //printf("realnum:%lf\n",realnum);
          if (concept=='I')I=realnum;
          if (concept=='U')U=realnum;
          if (concept=='P')P=realnum;
        }
      }
      printf("Problem #%d\n",i);
      //printf("%lf %lf %lf\n",P,U,I);
    if(I==0)  {double ans=P/U;printf("I=%.2fA\n",ans);}
    else if(U==0)  {double ans=P/I;printf("U=%.2fV\n",ans);}
    else if(P==0)  {double ans=I*U;printf("P=%.2fW\n",ans);}
    printf("\n");
  }
  return 0;
}