Pattern of right angle triangle ,right angled from right side using C++

Triangle angle triangle pattern  

You must aware of basic concept of loop.

#include <iostream>
using namespace std;
int main() {
  int a,b,s,row=5;
//this loop will print new line 
  for(a=1;a<=row;a++){
  //this loop will print space required in line
      for(s=a;s<=row;s++){
          cout<<" ";
      }
   //this loop print the number
      for(b=a;b>=1;b--){
          cout<<b;
      }
      cout<<endl;
  }
    return 0;
}