Print stairs path

// You are given a number n representing number of stairs in a staircase.
// You are standing at the bottom of staircase. You are allowed to climb 1 step, 2 steps or 3 steps in one move.
// Complete the body of printStairPaths function - without changing signature - to print the list of all paths that can be used to climb the staircase up.

void printStairsPath(int n, string str){
	 if(n < 0){
		 return ; 
	 }
	 if(n == 0){
		 cout << str << endl ; 
		 return ;
	 }
	 printStairsPath(n-1 , str + "1")  ;
	 printStairsPath(n-2 , str + "2")  ;
	 printStairsPath(n-3 , str + "3")  ;
}