class Main {
public static void main(String[] args) {
CountStairSteps cs = new CountStairSteps();
int stepsCount = CountStairSteps.countStairUpSteps(3);
System.out.println("stepsCount: "+stepsCount);
}
}
import java.util.*;
class CountStairSteps{
public static void main(String arg[]){
int n =5;
int stepsCount = countStairUpSteps(n);
System.out.println("stepsCount: "+stepsCount);
}
static ArrayList<Integer> al = new ArrayList<>();
public static int countStairUpSteps(int n){
//initizing arraylist
for(int i=0;i<=5;i++){
al.add(0);
}
if(n<0){
return -1;
}
if(n==0 || n==1){
return 1;
}
if(al.get(n)!=0)
return al.get(n);
int sum =countStairUpSteps(n-1)+countStairUpSteps(n-2);
al.set(n,sum);
return sum;
}
}
