UVA 10700 Camel trading

#include<stdio.h>
#include<string.h>
#include<ctype.h>
char b[1000];
double stack[10000];
int main()
{
int i,j,k,t,head,top;
double d,min,max,temp;
char flag;
scanf("%d",&t);
while(t--)
{
scanf("%s",b);
k=strlen(b);
head=top=0;
min=0.0;
b[k]='+';
for(i=0;i<=k;i++)
if(!isdigit(b[i]))
{
flag=b[i];
b[i]='\0';
sscanf(&b[head],"%lf",&d);
b[i]=flag;
stack[top++]=d;
if(flag=='+')
{
temp=1.0;
while(top)
{
top--;
temp*=stack[top];
}
min+=temp;
}
head=i+1;
}
temp=0.0;
head=0;
max=1.0;
b[k]='*';
for(i=0;i<=k;i++)
if(!isdigit(b[i]))
{
flag=b[i];
b[i]='\0';
sscanf(&b[head],"%lf",&d);
temp+=d;
if(flag=='*')
{
max*=temp;
temp=0.0;
}
head=i+1;
}
printf("The maximum and minimum are %.0f and %.0f.\n",max,min);
}
return 0;
}