StairCase.txt

Staircase
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A child is running up a staircase with N steps, and can hop either 1 step, 2 steps or 3 steps at a time. Implement a method to count how many possible ways the child can run up to the stairs. You need to return number of possible ways W.
Input format :
Integer N
Output Format :
Integer W
Constraints :
1 <= N <= 30
Sample Input 1 :
4
Sample Output 1 :
7
Sample Input 2 :
5
Sample Output 2 :
13


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public class Solution {
     public static int staircase(int n){
	 if(n<0)
	   return 0;
	 if(n == 0)
	 return 1;

	 int opt1 = staircase(n-1);
	 int opt2 = staircase(n-2);
	 int opt3 = staircase(n-3);

	 return opt1 + opt2 + opt3;  

	}
	
}