Perhaps #4 is about a test without the back wall. Here come some questions:
1. Should we assume the back wall to be located in the n+1 - th ?
2. It seems that the second scanning is from the back. So the FIRST maximum refers to the one who is leftmost or the rightmost?

Test:
15 5
10 12 10
10 12 10  0.01

3
4
5
95
95

96
6
97
97
98

99
99
99
97
99

What is answer?
My answer is:
Surface found at 4.
Bottom found at 5.
Channel 1: No object.
Channel 2: No object.

Why it is not correct?

В двух местах "число не превышающие 35" следует заменить на "число, не превышающее 35".

1.
"And you should take into account that someplace before this number in the sequence there must be a number not exceeding 35, otherwise it's not a wall, it's … well, you don't have to know what."

Does it need to check?

2.Сan there be objects in the same position?

Edited by author 13.07.2012 03:37

It seems there are extra characters in test 6!

I use following construction:
while (scanf("%d") != EOF)) {
  //proccess test
}
to be able to proccess several test from one file.

With this construction i got WA6. When i proccessed only one test i got Accepted.

It's something awful! There is no bottom in this test. But it does not mean that you should not analyse the channels! You just should think that bottom is n+1!
GOOD LUCK! And get AC!

const
  eps=0;
var
  b:array[1..10000] of extended;
  n,d,s1,e1,s2,e2:integer;
  l1,l2:extended;
  a:extended;
  i,f,back:integer;
  frontsearch,frontfound,backsearch,backfound:Boolean;
procedure SearchForFrontWall;
var
  i:integer;
begin
  i:=0;
  frontsearch:=false;
  frontfound:=false;
  repeat
    inc(i);
    frontsearch:=b[i]-35<=eps
  until (i=n) or frontsearch;
  if frontsearch then
    begin
      repeat
        inc(i);
        frontfound:=b[i]-95>=eps
      until (i=n) or frontfound;
      if frontfound then
        begin
          f:=i;
          writeln('Surface found at ',f,'.')
        end
    end
end;
procedure SearchForBackWall;
var
  i:integer;
begin
  i:=f;
  backsearch:=false;
  backfound:=false;
  repeat
    inc(i);
    backsearch:=b[i]-35<=eps
  until (i=n) or backsearch;
  if backsearch then
    begin
      if i<f+d-1 then
        i:=f+d-1;
      repeat
        inc(i);
        backfound:=b[i]-95>=eps
      until (i=n) or backfound
    end;
  if backfound then
    begin
      back:=i-f;
      writeln('Bottom found at ',back,'.')
    end
  else
    begin
      writeln('No bottom.');
      back:=n-f+1
    end;
end;
procedure SearchChannel(num,s,e:integer;l:extended);
var
  i,m:integer;
begin
  if s>=back then
    writeln('Channel ',num,': No search.')
  else
    begin
      m:=s;
      if e>=back then
        e:=back-1;
      for i:=s+1 to e do
        if b[i+f]-b[m+f]>eps then
          m:=i;
      if b[m+f]-l>eps then
        writeln('Channel ',num,': Object at ',m,'.')
      else
        writeln('Channel ',num,': No object.')
    end
end;
begin
  readln(n,d,s1,e1,l1,s2,e2,l2,a);
  for i:=1 to n do
    readln(b[i]);
  SearchForFrontWall;
  if frontfound then
    begin
      for i:=f+1 to n do
        b[i]:=b[i]*(1+(i-f)*a);
      SearchForBackWall;
      SearchChannel(1,s1,e1,l1);
      SearchChannel(2,s2,e2,l2)
    end
  else
    writeln('No surface.')
end.

#include <stdio.h>

int N, D, S1, E1, L1, S2, E2, L2;
double A, arr[10001];

int main()
{
    int i, start = 0, end = 0, one, pos1 = 0, pos2 = 0;
    arr[0] = -1e10;

//    freopen("input.txt", "r", stdin);
//    freopen("output.txt", "w", stdout);


    scanf("%d %d %d %d %d %d %d %d %lf", &N, &D, &S1, &E1, &L1, &S2, &E2, &L2, &A);
    for (i = 1; i <= N; i++)
        scanf("%lf", &arr[i]);

    for (i = 1; i <= N; i++)
    {
        if (arr[i] <= 35) break;
    }

    for (++i; i <= N; i++)
    {
        if (arr[i] >= 95)
        {
            start = i;
            break;
        }
    }

    if (start == 0)
    {
        printf("No surface.\n");
        return 0;
    }
    else
    {
        printf("Surface found at %d.\n", start);
    }

    for (i = start; i <= N; i++)
    {
        arr[i] *= 1 + (i - start) * A;
    }


    for (i = start + 1; i <= N; i++)
    {
        if (arr[i] <= 35) break;
    }

    if (i < start + D) i = start + D;

    for (; i <= N; i++)
    {
        if (arr[i] >= 95)
        {
            end = i;
            break;
        }
    }

    if (end == 0)
    {
        printf("No bottom.\n");
        end = N;
    }
    else
    {
        printf("Bottom found at %d.\n", end - start);
    }

    S1 += start;
    E1 += start;
    if (E1 > end) E1 = end;
    one = 0;

    for (i = S1; i <= E1; i++)
    {
        one = 1;

        if (arr[i] > arr[pos1]) pos1 = i;
    }

    if (one == 0)
    {
        printf("Channel 1: No search.\n");
    }
    else
    {
        if (arr[pos1] >= L1) printf("Channel 1: Object at %d.\n", pos1 - start);
        else printf("Channel 1: No object.\n");
    }

    S2 += start;
    E2 += start;
    if (E2 > end) E2 = end;
    one = 0;

    for (i = S2; i <= E2; i++)
    {
        one = 1;

        if (arr[i] > arr[pos2]) pos2 = i;
    }

    if (one == 0)
    {
        printf("Channel 2: No search.\n");
    }
    else
    {
        if (arr[pos2] >= L2) printf("Channel 2: Object at %d.\n", pos2 - start);
        else printf("Channel 2: No object.\n");
    }

    return 0;
}

#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;
}