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  1. program mountain;
  2. Uses sysutils, Math;
  3.  
  4. const
  5.     MAXN = 100005;
  6.  
  7. Type elenco= Array of LongInt;
  8.  
  9. var
  10.     ANS, N, i, id, x, maxMountainLength, lung, len, count : LongInt;
  11.     P, leftLIS, rightLIS, valli: Array[0..MAXN-1] of LongInt;
  12.     LIS : elenco;
  13.     rimossi : Ansistring;
  14.  
  15.  
  16.  
  17. Procedure ricercaUpper (var w:elenco; target:Longint); (*ritorna indice del valore maggiore/uguale a target oppure -1 se non esiste*)
  18.   var m,start,eend: Longint;
  19.  
  20.  begin  
  21.    start:=0; eend:=len-1 ; m:=-1;
  22.    while start<=eend do
  23.            begin
  24.                   m:=(start + eend) div 2;
  25.                   if w[m]<target then  start:=m+1
  26.                                  else  if w[m]>=target then  begin id:=m;  eend:=m-1 end;
  27.            end;
  28.    if start=len then id:=-1;
  29.  
  30.  end;
  31.  
  32.  
  33.  
  34.  
  35. begin
  36.     (*assign(input,  'input.txt');  reset(input);
  37.     assign(output, 'output.txt'); rewrite(output); *) 
  38.  
  39.     ReadLn(N);
  40.     rimossi:=''; lung:=N;  
  41.     for i:=0 to N-1 do begin
  42.                         Read(P[i]);
  43.                         rimossi:=rimossi+IntTostr(P[i]);
  44.                         valli[i]:=0; 
  45.                        end;  
  46.     ReadLn();
  47.      count:=0;
  48.      i:=2; 
  49.  
  50.         while i<lung do
  51.               begin
  52.                 if  (rimossi[i]<rimossi[i-1]) and (rimossi[i]<rimossi[i+1])                    
  53.                                       then
  54.                                            begin
  55.                                                 if (i+count)<lung then valli[i+count]:=-1;
  56.                                                 delete(rimossi,i,1);
  57.                                                 lung:=lung-1;  count:=count+1;
  58.                                                 setLength(rimossi,lung);                                                                                                                                     i:=i+1;
  59.                                             end
  60.                                        else i:=i+1;
  61.               end; 
  62.  
  63.     ANS := 0; 
  64. 	(*leftLIS[i] stores the length of longest increasing subsequence ending at index i*)
  65. 	(*rightLIS[i] stores the length of longest decreasing subsequence starting at index i*)
  66.     len:=1; SetLength(LIS,len); LIS[0]:=P[0];
  67.     for i:=0 to  N-1 do begin leftLIS[i]:=1; rightLIS[i]:=1; end;
  68.     (*Calculate LIS from left to right for each position*)
  69.     for i :=1 to N-1 do
  70.                     begin
  71.                         if valli[i]=0 then 
  72.                          begin 
  73.                            ricercaUpper(Lis, P[i]);
  74.                            // if element in not present in lis insert at the end
  75.  
  76.                            if id=-1 then
  77.                                    begin
  78.                                      len:=len+1;
  79.                                      SetLength(LIS,len);
  80.                                      LIS[len-1] := P[i];
  81.                                      leftLIS[i]:=len;
  82.                                    end
  83.                                  else
  84.                                     begin
  85.                                       // if element is to be inserted in lis
  86.                                       if (id<>0) and (valli[id]=-1) then
  87.                                                      begin
  88.                                                         LIS[id] := P[i];
  89.                                                         leftLIS[i]:=id+1;                                                       
  90.                                                      end
  91.                                                else 
  92.                                                 leftLIS[i]:=0;
  93.  
  94.                                     end; 
  95.                           end 
  96.  
  97.                         else  leftLIS[i]:=0;                  
  98.              end;      
  99.  
  100.        (* Calculate LIS from right to left (decreasing subsequence) for each position*)
  101.  
  102.    len:=1; SetLength(LIS,len); LIS[0]:=P[N-1]; 
  103.  
  104.    for i :=N-2  downto 0 do
  105.                     begin
  106.                         ricercaUpper(Lis, P[i]);
  107.                         if id=-1 then
  108.                                    begin
  109.                                      len:=len+1;
  110.                                      SetLength(LIS,len);
  111.                                      LIS[len-1] := P[i];
  112.                                      rightLIS[i]:=len;
  113.                                    end
  114.                                  else
  115.                                     begin
  116.                                       // if element is to be inserted in lis
  117.                                       if (id<>0) and (valli[N-1-id]=-1) then
  118.                                                      begin
  119.                                                         LIS[id] := P[i];
  120.                                                         rightLIS[i]:=id+1;                                                        
  121.                                                      end
  122.                                                 else  
  123.                                                    rightLIS[i]:=0;
  124.  
  125.  
  126.                                    end;                    
  127.                     end;
  128.  
  129.     maxMountainLength := 0;
  130.     (* Find the maximum length of mountain subsequence*)
  131.     // for every index check for longest mountain array,
  132.     for i := 0 to N-1 do
  133.              begin
  134.                 if (leftLIS[i] >=1) AND (rightLIS[i] >= 1) then 
  135.                       begin
  136.                         x := leftLIS[i] + rightLIS[i] - 1;
  137.                         maxMountainLength := max(maxMountainLength, x);
  138.                       end;  
  139.              end;
  140.     // returning removals
  141.  
  142.    ANS:= N - maxMountainLength; 
  143.    WriteLn(ANS);
  144. end.
Success #stdin #stdout 0s 5324KB
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https://ideone.com/fWPVra
language:
Pascal (fpc 3.0.4)
created:
20 hours ago
visibility:
public

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