cc150_9_1.java

public class Q9_1 {
	
	public static void main(String[] args){
		int test = 10;
		System.out.println("Total Stair No.: "+test);
		
		int[] maptest = new int [test];
		for (int i=0;i < maptest.length;i++){
			maptest[i] = -1;
		}
		System.out.println("Result.: "+ countWays(test,maptest));
	}
	
	public static int countWays(int n, int[] map){
		//System.out.println(n);
		

		if (n < 0){
			
			return 0;
		}
		else if (n == 0)
			return 1;
		
//		else{
//			return countWays(n-1)+countWays(n-2)+countWays(n-3);
//		}
		
		else if(map[n-1] >= 0){
			
			return map[n-1];
		}
		else{
			
			map[n-1] = countWays(n-1, map)+countWays(n-2,map)+countWays(n-3,map);
			return map[n-1];
		}
		
	}

}