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  1. program pens;
  2.  
  3. const
  4.     MAXN = 1000000;
  5.  
  6. var
  7.     N, i, senzapenna  : longint;
  8.     pen  : array[0..MAXN-1] of longint;
  9.  
  10. begin
  11. {
  12.     uncomment the following lines if you want to read/write from files
  13.     assign(input,  'input.txt');  reset(input);
  14.     assign(output, 'output.txt'); rewrite(output);
  15. }
  16.  
  17.     readln(N);
  18.     for i:=0 to N-1 do
  19.         read(pen[i]);
  20.     readln();
  21.     if N=1 then begin if pen[0]=0 then senzapenna:=1
  22.                                   else senzapenna:=0;
  23.                 end                
  24.            else
  25.              begin
  26.                senzapenna:=0;
  27.                if pen[0]=0 then begin if pen[1]>1 then begin pen[0]:=pen[0]+1; pen[1]:=pen[1]-1; end
  28.                                                   else senzapenna:=senzapenna+1; 
  29.                                  end;
  30.                for i:=1 to N-2 do 
  31.                      begin 
  32.                        if pen[i]=0 then begin if pen[i-1]>1 then begin pen[i]:=pen[i]+1; pen[i-1]:=pen[i-1]-1; end
  33.                                                             else begin if pen[i+1]>1 then begin pen[i]:=pen[i]+1; pen[i+1]:=pen[i+1]-1; end
  34.                                                                        else senzapenna:=senzapenna+1;
  35.                                                                   end;
  36.                                         end;
  37.                      end;
  38.                if pen[N-1]=0 then begin  if pen[N-2]>1 then begin pen[N-1]:=pen[N-1]+1; pen[N-2]:=pen[N-2]-1; end
  39.                                                         else senzapenna:=senzapenna+1; 
  40.                                   end;
  41.             end;                      
  42.     writeln(senzapenna); { answer }
  43. end.
  44.  
  45.  
Success #stdin #stdout 0s 5288KB
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https://ideone.com/FczlOB
language:
Pascal (fpc 3.0.4)
created:
39 days ago
visibility:
public

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