Câu 2: 

uses crt;

var a,b:array[1..100]of integer;

i,n,t,dem,j,kt,dem1:integer;

begin

clrscr;

readln(n);

for i:=1 to n do 

readln(a[i]);

t:=0;

for i:=1 to n do t:=t+a[i];

writeln(t);

dem:=1;

b[1]:=a[1];

for i:=1 to n do 

begin

kt:=0;

for j:=1 to dem do

  if b[j]=a[i] then kt:=1;

if kt=0 then 

begin

inc(dem);

b[dem]:=a[i];

end;

end;

for i:=1 to dem do 

begin

dem1:=0;

for j:=1 to n do 

  if a[j]=b[i] then inc(dem1);

writeln(b[i],' xuat hien ',dem1,' lan');

end;

readln;

end.

def tach_chuoi(chuoi):

     ky_tu_so = " "

     ky_tu_chu = " "

     for ky_tu in chuoi:

          if ky_tu.isdigit():

               ky_tu_so += ky_tu

          elif ky_tu.isalpha():

               ky_tu_chu += ky_tu

     return ky_tu_so, ky_tu_chu

chuoi = input("Nhập vào một chuỗi: ")

ky_tu_so, ky_tu_chu = tach_chuoi(chuoi)

print("Các ký tự số trong chuỗi:", ky_tu_so)

print("Các ký tự chữ cái trong chuỗi:", ky_tu_chu)

uses crt;

var st:string;

d,i:integer;

begin

clrscr;

readln(st);

d:=length(st);

for i:=1 to d do

if (st[i] in ['a'..'z']) then write(st[i]);

writeln;

for i:=1 to d do

if (st[i] in ['0'..'9']) then write(st[i]);

readln;

end.

#include <bits/stdc++.h>
using namespace std;
int main() {
    string str;
    getline(cin, str);
    string ans = "";
    for (char c : str) {
        if (!isdigit(c)) {
            ans += c;
        }
    }
    cout <<ans;
}

Theo mk là như v

uses crt;

var st:string;

d,i:integer;

begin

clrscr;

readln(st);

d:=length(st);

for i:=1 to d do

if not(st[i] in ['0'..'9']) then write(st[i]);

readln;

end.

uses crt;

var s:string;

i,d,dem:integer;

begin 

clrscr;

write('Nhap chuoi S:'); readln(s);

d:=length(s);

writeln('Trong chuoi ',s,' co ',d,' ki tu');

writeln('Chuoi dao cua chuoi ',s,' la: ');

for i:=d downto 1 do 

  write(s[i]:4);

writeln;

dem:=0;

for i:=1 to d do 

  if s[i] in ['0'..'9'] then inc(dem);

writeln('So chu so trong xau la: ',dem);

readln;

end. 

#include <bits/stdc++.h>

using namespace std;

int main()

{

string st;

int d,i,dem=0;

getline(cin,st);

d=st.length();

for (int i=0; i<d; i++)

if (st[i]=' ') dem++;

cout<<dem+1;

return 0;

}

uses crt;

var s:string;

i,tong,x,code:integer;

f,g:text;

k:boolean;

const fi='XAU.INP'

          fo='XAU.OUT'

begin

k:=false;

assign(f,fi); reset(f);

assign(g,fo); rewrite(g);

readln(f,s);

tong:=0;

for i:=1 to length(s) do

begin

if s[i] in ['0'..'9'] then

begin

k:=true;

val(s[i],x,code);

tong:=tong+x;

x:=0;

cod:=0;

end;

end;

if k=false then writeln(g,'Sai yeu cau')

else

begin

writeln(g,s);

writeln(g,tong);

end;

close(f);

close(g);

end.

xau = input('Nhập xâu kí tự: ')

chu_cai, chu_so, ki_tu_khac = 0, 0, 0

for kt in xau:

      if kt.isalpha():

            chu_cai += 1

      elif kt.isdigit():

            chu_so += 1

      else:

            ki_tu_khac += 1

print('Số lượng kí tự chữ cái:', chu_cai)

print('Số lượng kí tự chữ số:', chu_so)

print('Số lượng kí tự khác:', ki_tu_khac)