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Discussion of Problem 1288. Astrolocation

Help! Can anyone point out why my program got WA on test 5?
Posted by Dragon 18 Feb 2005 08:05
#include <stdio.h>
#include <stdlib.h>
#define infile "1288.in3"
#define outfile "1288.ou3"
#define maxn 10100
#define zero 1e-6

double a[maxn+1],xs;
long n,d,front,back,s[3],e[3],l[3];

FILE *fin=stdin,
     *fout=stdout;

void init()
{
 long i;
 fscanf(fin,"%ld%ld",&n,&d);
 for (i=1; i<=2; i++)
  fscanf(fin,"%ld%ld%ld",&s[i],&e[i],&l[i]);
 fscanf(fin,"%lf",&xs);
 for (i=1; i<=n; i++)
  fscanf(fin,"%lf",&a[i]);
 fclose(fin);
}

void find_front_wall()
{
 long i,you=0;
 for (i=1; i<=n; i++)
  if (a[i]<=35+zero)
   you=1;
   else if ((a[i]>=95-zero)&&(you))
         {
          front=i;
          return;
         }
 fprintf(fout,"No surface.\n");
 fclose(fout);
 exit(0);
}

void change()
{
 long i;
 for (i=front+1; i<=n; i++)
  a[i]=a[i]*(1+(i-front+0.0)*xs);
}

long find_back_wall()
{
 long i,you=0;
 if (front+d>n)
  return 0;
 for (i=front+1; i<front+d; i++)
  if (a[i]<=35+zero)
   you=1;
 for (i=front+d; i<=n; i++)
  if (a[i]<=35+zero)
   you=1;
   else if ((a[i]>=95-zero)&&(you))
         {
          back=i;
          return 1;
         }
 back=n+1; //special!!!
 return 0;
}

long min(long a,long b)
{
 if (a<b)
  return a;
  else return b;
}

void zhao(long sign,long s,long e,long l)
{
 long i,j;
 if (front+s>back-1)
  {
   fprintf(fout,"Channel %ld: No search.\n",sign);
   return;
  }
 s=front+s;
 e=min(front+e,back-1);
 j=s;
 for (i=s; i<=e; i++)
  if (a[i]>a[j]+zero)
   j=i;
 if (a[j]>l-zero)
  fprintf(fout,"Channel %ld: Object at %ld.\n",sign,j-front);
  else fprintf(fout,"Channel %ld: No object.\n",sign);
}

void work()
{
 find_front_wall();
 change();
 fprintf(fout,"Surface found at %ld.\n",front);
 if (find_back_wall())
  fprintf(fout,"Bottom found at %ld.\n",back-front);
  else fprintf(fout,"No bottom.\n");
 zhao(1,s[1],e[1],l[1]);
 zhao(2,s[2],e[2],l[2]);
 fclose(fout);
}

int main()
{
 init();
 work();
 return 0;
}