mar06_21_NK_Factorial.java

/*   Created by IntelliJ IDEA.
 *   Author: Kshitij Varshney (kshitijvarshne1)
 *   Date: 06-Mar-21
 *   Time: 1:32 AM
 *   File: Factorial.java
 */

package March.mar06_21_NK;

import java.util.Scanner;

public class Factorial {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int number = sc.nextInt();
        System.out.println(factorial(number));
    }

    private static int factorial(int n) {
        if (n == 1 || n == 0) {
            return 1;
        }
        return n * factorial(n - 1);
    }
}

mar06_21_NK_Fibonacci.java

/*   Created by IntelliJ IDEA.
 *   Author: Kshitij Varshney (kshitijvarshne1)
 *   Date: 06-Mar-21
 *   Time: 1:36 AM
 *   File: Fibonacci.java
 */

package March.mar06_21_NK;

import java.util.Scanner;

public class Fibonacci {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        System.out.println(fibonacci(n));
        for (int i = 0; i < n + 1; i++) {
            System.out.print(fibonacci(i) + " ");
        }
    }

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

mar06_21_NK_FibonacciUsingIteration.java

/*   Created by IntelliJ IDEA.
 *   Author: Kshitij Varshney (kshitijvarshne1)
 *   Date: 06-Mar-21
 *   Time: 1:51 AM
 *   File: FibonacciUsingIteration.java
 */

package March.mar06_21_NK;

import java.util.Scanner;

public class FibonacciUsingIteration {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int a = 0;
        int b = 1;
        System.out.print(a + " " + b + " ");
        for (int i = 2; i <= n; i++) {
            System.out.print(a + b + " ");
            int c = a + b;
            a = b;
            b = c;
        }
    }
}

mar06_21_NK_SecondLargestElement.java

/*   Created by IntelliJ IDEA.
 *   Author: Kshitij Varshney (kshitijvarshne1)
 *   Date: 06-Mar-21
 *   Time: 3:17 PM
 *   File: SecondLargestElement.java
 */

package March.mar06_21_NK;

import java.util.Stack;

public class SecondLargestElement {
    public static void main(String[] args) {
        int[] a = {6, 9, 3, 4, 5};
        System.out.println(find(a));
    }

    private static int find(int[] a) {
        Stack<Integer> stack = new Stack<>();
        for (int i : a) {
            if (stack.size() < 2) {
                if (stack.size() == 0) {
                    stack.push(i);
                } else {
                    if (stack.peek() > i) {
                        stack.push(i);
                    } else {
                        int x = stack.pop();
                        stack.push(i);
                        stack.push(x);
                    }
                }
            } else if (stack.peek() < i) {
                int temp = stack.pop();
                if (stack.peek() < i) {
                    int x = stack.pop();
                    stack.push(i);
                    stack.push(x);
                } else {
                    stack.push(i);
                }
            }
        }
        return stack.pop();
    }
}

mar06_21_NK_TowerOfHanoi.java

/*   Created by IntelliJ IDEA.
 *   Author: Kshitij Varshney (kshitijvarshne1)
 *   Date: 06-Mar-21
 *   Time: 1:22 AM
 *   File: TowerOfHanoi.java
 */

package March.mar06_21_NK;

import java.util.Scanner;

public class TowerOfHanoi {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int numberOfDisc = sc.nextInt();
        towerOfHanoi(numberOfDisc, 'A', 'H', 'D');
    }

    public static void towerOfHanoi(int n, char s, char h, char d) {
        if (n >= 1) {
            towerOfHanoi(n - 1, s, d, h);
            System.out.println(n + " " + s + " -> " + d);
            towerOfHanoi(n - 1, h, s, d);
        }
    }
}