1. Print number in decreasing order

public static void decreasing_order(int n) {
        if(n == 1){ //base case
            System.out.println(n);
            return;
        }
        System.out.print(n + " ");// kaam karna
        decreasing_order(n-1);// inner func call karna
    }

1. Print factorial of a number

public static int fact(int n) {
        if (n == 0) {
            return 1;
        }
        
        return n * fact(n-1);
    }

1. Fibonacci number

public static int fibbo(int n) {
        if ( n == 0) {
            return 0;
        }
        if (n == 1 || n == 2) {
            return 1;
        }
        return fibbo(n-1) + fibbo(n-2);
    }

1. Check Given Array is sorted or not??

public static boolean issorted(int arr[] , int i) {
        if (i == arr.length - 1) {
            return true;
        }
        if (arr[i] > arr[i+1]) {
            return false;
        }
        return issorted(arr, i+1);
    }

1. Find first Occurance of an element in array

public static int firstoccur(int arr[] , int key , int i) {
        if ( i == arr.length - 1) {
            return -1;
        }
        if (arr[i] == key) {
            return i;
        }
        return firstoccur(arr, key, i+1);
    }

1. Print X to the power n

if (n==0) {
            return 1;
        }
        return x * pow(x, n-1);

1. Tiling Problems