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

Code mẫu của ladpro98

#include <iostream>
#include <cstdio>
#include <vector>
#define REP(i, a, b) for(int i = (a); i <=(b); ++i)

const int N = 110;

using namespace std;

int n, m, k;
int a[N][N], mask[N];
vector<bool> ok (1 << 26);
char s[N];

void backtrack(int i, int now, int cntNow) {
    if (cntNow == k) {
        ok[now] = 1;
        return;
    }
    backtrack(i + 1, now | (1 << i), cntNow + 1);
    if (cntNow + 25 - i >= k)
        backtrack(i + 1, now, cntNow);
}

int main() {
    #ifdef _LAD_
        freopen("KRECT.inp", "r", stdin);
    #endif // _LAD_
    scanf("%d %d %d\n", &m, &n , &k);
    REP(i, 1, m) {
        scanf("%s\n", s + 1);
        REP(j, 1, n)
            a[i][j] = s[j] - 'A';
    }
    backtrack(0, 0, 0);
    int rect = 0, ans = 0;
    REP(i, 1, m) {
        REP(j, 1, n) mask[j] = 0;
        REP(j, i, m) {
            REP(col, 1, n)
                mask[col] |= 1 << a[j][col];
            REP(l, 1, n) {
                rect = 0;
                REP(r, l, n) {
                    rect |= mask[r];
                    ans += ok[rect];
                }
            }
        }
    }
    cout << ans << endl;
    return 0;
}

Code mẫu của RR

{$MODE OBJFPC}

uses math;
const
  FINP          =       '';
  FOUT          =       '';
  MAXN          =       101;

var
  f1,f2         :       text;
  m,n,k         :       longint;
  a             :       array[1..MAXN,1..MAXN] of char;
  count         :       array[1..MAXN,'A'..'Z'] of 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
      i,j:longint;
    begin
      readln(f1,m,n,k);
      for i:=1 to m do
        begin
          for j:=1 to n do read(f1,a[i,j]);
          readln(f1);
        end;
    end;

var
  now:longint;
  all:array['A'..'Z'] of longint;

procedure add(i:longint); inline;
    var
      c:char;
    begin
      for c:='A' to 'Z' do
      if count[i,c]>0 then
        begin
          if all[c]=0 then inc(now);
          inc(all[c],count[i,c]);
        end;
    end;

procedure del(i:longint); inline;
    var
      c:char;
    begin
      for c:='A' to 'Z' do
      if count[i,c]>0 then
        begin
          dec(all[c],count[i,c]);
          if all[c]=0 then dec(now);
        end;
    end;

function get(x:longint):longint; inline;
    var
      l,r,i,j,res:longint;
    begin
      res:=0;
      for l:=1 to m do
        begin
          fillchar(count,sizeof(count),0);
          for r:=l to m do
            begin
              for i:=1 to n do
                inc(count[i,a[r,i]]);
              fillchar(all,sizeof(all),0);
              now:=0;
              j:=1;
              for i:=1 to n do
                begin
                  add(i);
                  while now>x do
                    begin
                      del(j);
                      inc(j);
                    end;
                  inc(res,i-j+1);
                end;
            end;
        end;
      exit(res);
    end;

begin
  openF;
  inp;
  writeln(f2,get(k)-get(k-1));
  closeF;
end.

Code mẫu của hieult

#include<cstdio>
#include<cmath>
#include<cstring>
#include<cstdlib>
#include<cassert>
#include<ctime>
#include<algorithm>
#include<iterator>
#include<iostream>
#include<cctype>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<list>
//#include<conio.h>
#define ep 0.2
#define maxn 1502
#define oo 1111111111
#define base 100000000
#define TR(c, it) for(typeof((c).begin()) it=(c).begin(); it!=(c).end(); it++)
double const PI=4*atan(1);

using namespace std;

typedef pair<int, int> II;
typedef vector<int> VI;
typedef vector<II> VII;
typedef vector<VI> VVI;
typedef vector<VII> VVII;

char s[102];
int f[30][102][102],t[30],so;
int n,m,k;

int xuly(int k){
     int KQ = 0;
    int u,v;
     for(int i = 1;i<=m;i++)
          for(int j=i;j<=m;j++){
                v = 0; memset(t,0,sizeof(t));
                for(u = 1 ;u<=n;u++){
                      for(int x = 0;x<='Z'-'A';x++)
                            t[x]-=(f[x][u-1][j]-f[x][u-1][i-1]);
                      while(v<n+1){
                            so = 0;       
                            for(int x = 0;x<='Z'-'A';x++) if(t[x]) so++;
                            if(so>=k)
                                 break;
                            v++;
                            for(int x = 0;x<='Z'-'A';x++)
                                 t[x]+=(f[x][v][j]-f[x][v][i-1]);                           
                      }
                      if(v>n) break;
                      else KQ+=n-v+1;
                }
          //if(k==4) printf("%d %d %d\n",i,j,KQ);       
          }
     return KQ;    
}

int main(){
    // freopen("KRECT.in","r",stdin);    
     scanf("%d %d %d",&n,&m,&k);
     memset(f,0,sizeof(f));
     for(int i = 1;i<=n;i++){
          scanf("%s",s);
          for(int j = 1;j<=m;j++)
               for(int k = 0;k<='Z'-'A';k++){
                     if(k+'A'==s[j-1])
                          f[k][i][j] = f[k][i][j-1]+1;
                     else f[k][i][j] = f[k][i][j-1];
               }
     }
    // printf("%d %d\n",xuly(k),xuly(k+1));
     printf("%d",xuly(k)-xuly(k+1));
    // getch();
}

Code mẫu của khuc_tuan

//{$APPTYPE CONSOLE}
 {$MODE DELPHI}

var
    z : array[1..100,0..25] of integer;
    d, e : array[0..25] of integer;
    m, n, k : integer;
    a : array[1..100,1..100] of char;

function get() : integer;
var
    r, i, j, j2, d1, d2, kk, kk2, t: integer;
begin
    r := 0;
    for d1:=1 to m do
    begin
        fillchar( z, sizeof(z), 0);
        for d2:=d1 to m do
        begin
            for i:=1 to n do
                inc( z[i, ord(a[d2,i]) - ord('A')] );
            kk := 0;
            kk2 := 0;
            j := 0;
            j2 := 0;
            fillchar( d, sizeof(d), 0);
            fillchar( e, sizeof(e), 0);
            for i:=1 to n do
            begin
                while (kk <= k) and (j<=n) do
                begin
                    inc(j);
                    if j>n then break;
                    for t:=0 to 25 do
                    begin
                        if (d[t]=0) and (z[j,t]>0) then inc(kk);
                        d[t] := d[t] + z[j,t];
                    end;
                end;

                while (kk2 < k) and (j2 <=n) do
                begin
                    inc(j2);
                    if j2 > n then break;
                    for t:=0 to 25 do
                    begin
                        if (e[t]=0) and (z[j2,t]>0) then inc(kk2);
                        e[t] := e[t] + z[j2,t];
                    end;
                end;

                r := r + j - j2;

                for t:=0 to 25 do
                begin
                    if (d[t]>0) and (d[t]=z[i,t]) then dec(kk);
                    d[t] := d[t] - z[i,t];

                    if (e[t]>0) and (e[t]=z[i,t]) then dec(kk2);
                    e[t] := e[t] - z[i,t];
                end;
            end;
        end;
    end;
    get := r;
end;

var
    i, j : integer;

begin
    readln(m, n, k);
    for i:=1 to m do
    begin
        for j:=1 to n do read(a[i,j]);
        readln;
    end;
    writeln( get());
end.