C++ Program:

Example:

1
2 2
3 3 3

#include <iostream>
using namespace std;

int main() {
  int rows;
  cout<<"Enter number of rows : ";
  cin>>rows;
  for(int i=1; i<=rows; i++) {
    for(int j=1; j<=i; j++) {
      cout<<i<<" ";
    }
    cout<<endl;
  }
  return 0;
}

Output:

  Enter number of rows : 4
  1
  2 2
  3 3 3
  4 4 4 4

Main logic :

for(int i=1; i<=rows; i++) {  //rows : number of rows to print
  for(int j=1; j<=i; j++) {
    cout<<i<<" ";
  }
  cout<<endl;
}