Lưu ý: Các code mẫu dưới đây chỉ mang tính tham khảo và có thể không AC được bài tập này

Code mẫu của flashmt

const fi='nknl.inp';
      fo='nknl.out';
var re,n:longint;
    s,a:array[0..250] of char;

procedure rf;
begin
     n:=0;
     while not eoln do
     begin
          inc(n);
          read(s[n]);
     end;
end;

procedure pr;
var i,x,y,p,q,nt:longint; kt:boolean;
begin
     re:=0;
     for p:=1 to n-4 do
     begin
          fillchar(a,sizeof(a),'0');
          for i:=p to p+3 do
              a[i-p]:=s[i];
          for q:=p+4 to n do
          begin
               a[q-p]:=s[q];
               nt:=q-p+1;
               x:=0; y:=1; kt:=true;
               while (x<nt) and (y<nt) and (x<y) and kt do
               begin
                    i:=0;
                    repeat
                          if a[(x+i) mod nt]<a[(y+i) mod nt] then
                          begin
                               y:=(y+i) mod nt + 1;
                               break;
                          end
                          else
                          begin
                               if a[(x+i) mod nt]>a[(y+i) mod nt] then
                               begin
                                    kt:=false;
                                    break;
                               end
                               else inc(i);
                          end;
                    until i=nt;
                    if i=nt then break;
               end;
               if kt then inc(re);
          end;
     end;
end;

procedure wf;
begin
     write(re);
end;

begin
     rf;
     pr;
     wf;
end.

Code mẫu của RR

{$MODE OBJFPC}

uses math;
const
  FINP          =       '';
  FOUT          =       '';
  MAXN          =       250;

var
  f1,f2         :       text;
  f             :       array[1..MAXN,1..MAXN,1..MAXN] of integer;
  s             :       string;
  n             :       longint;

procedure openF;
    begin
      assign(f1,FINP); reset(f1);
      assign(f2,FOUT); rewrite(f2);
    end;

procedure closeF;
    begin
      close(f1);
      close(f2);
    end;

procedure inp;
    var
      k,i,j:longint;
    begin
      readln(f1,s); n:=length(s);

      for i:=1 to n-1 do
      for j:=i+1 to n do
        if s[i]>s[j] then f[1,i,j]:=1
        else if s[i]=s[j] then f[1,i,j]:=0
        else f[1,i,j]:=-1;

      for k:=2 to n-1 do
      for i:=1 to n-k do
      for j:=i+1 to n-k+1 do
        if f[k-1,i,j]<>0 then f[k,i,j]:=f[k-1,i,j]
        else
          if s[i+k-1]>s[j+k-1] then f[k,i,j]:=1
          else if s[i+k-1]=s[j+k-1] then f[k,i,j]:=0
          else f[k,i,j]:=-1;
    end;

function check(i,j:longint):boolean;
    var
      u,v,k:longint;
    begin
      u:=j-i+1; v:=0;
      for k:=i+1 to j do
        begin
          dec(u); inc(v);
          if (f[u,i,k]=1) then exit(false);
          if (f[u,i,k]=0) and (f[v,i,j-v+1]=-1) then exit(false);
        end;
      exit(true);
    end;

procedure solve;
    var
      i,j,res:longint;
    begin
      res:=0;
      for i:=1 to n-4 do
      for j:=i+4 to n do
        if check(i,j) then
            inc(res);
      writeln(f2,res);
    end;

begin
  openF;
  inp;
  solve;
  closeF;
end.

Code mẫu của hieult

#include <stdio.h>
//#include <conio.h>
#include <string.h>
#define maxn 251

char s[maxn];
int f[maxn][maxn];

int main()
{
    //freopen("NKNL.in","r",stdin);
    scanf("%s",s);
    int n = strlen(s);
    for(int i = 0;i<=n-1;i++)
    {
        if(s[i] != s[n-1])
        {
            f[i][n-1] = 0;
            f[n-1][i] = 0;
        }
        else
        {
            f[i][n-1] = n;
            f[n-1][i] = n;
        }
    }
    for(int i = n-2;i>=0;i--)
    {
        for(int j = 0;j<=i;j++)
        {
            if(s[i]!=s[j])
            {
                f[i][j] = 0;
                f[j][i] = 0;
            }
            else
            {
                f[i][j] = f[i+1][j+1]+1;
                f[j][i] = f[i][j];
            }
        }
    }
    int KQ = 0;
    for(int i = 5;i<=n;i++)
        for(int u = 0;u<=n-i;u++)
        {
             int flag = 0;
             for(int j = 1;j<=i-1;j++)
             {
                  if(f[u][u+j]+j<=i-1)
                  {
                      if(s[u+j+f[u][u+j]]<s[u+f[u][u+j]])
                      {
                          flag = 1;
                          break;
                      }
                  }
                  else if(f[u][u+i-j]+u+i-j<=u+i-1)
                  {
                       if(s[f[u][u+i-j]+u+i-j]>s[u+f[u][u+i-j]])
                       {
                           flag = 1;
                           break;
                       }
                  }
             }
             if(flag == 0)
             {
                 KQ++;
             }
        }
    printf("%d",KQ);
   // getch();
}

Code mẫu của khuc_tuan

#include <stdio.h>
#include <string.h>

char a[255];
int n;
int F[255][255];

int main() {
    gets(a);
    n = strlen(a);
    for(int i=n-1;i>=0;--i)
        for(int j=n-1;j>=i;--j) {
            if(a[i]!=a[j]) F[i][j] = 0;
            else if(i==n-1 || j==n-1) F[i][j] = 1;
            else F[i][j] = F[i+1][j+1] + 1;
        }
    int dem = 0;
    for(int st=0;st<n;++st) for(int en=st;en<n;++en) if(en-st+1 >= 5) {
        bool ok = true;
        for(int i=st+1;i<=en;++i) {
            // compare a[st->en]  |   a[i->en + st -> (i-1)] 
            int z = F[st][i];
            if(z<en-i+1 && a[st+z] > a[i+z]) { ok = false; break; }
            else if(z>=en-i+1) {
                z = F[st][st+en-i+1];
                if(z<i-st && a[st+z] < a[st+en-i+1+z]) { ok = false; break; }
            }
        }
        if(ok) ++dem;
    }
    printf("%d\n", dem);
    return 0;
}