Fibonacci and Factorial

Factorial.java

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+import java.util.*;
+
+public class Factorial {
+    public static void calculateFactorial(int n) {
+        if (n < 0) {
+            System.out.println("Invalid Number");
+            return;
+        }
+        int factorial = 1;
+        for (int i = n; i >= 1; i--) {
+            factorial = factorial * i;
+        }
+        System.out.println(factorial);
+        return;
+    }
+
+    public static void main(String args[]) {
+        Scanner sc = new Scanner(System.in);
+        int n = sc.nextInt();
+        calculateFactorial(n);
+    }
+}

FactorialByRecursion.java

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+public class FactorialByRecursion {
+    public static int calcfactorial(int n) {
+        if (n == 1 || n == 0) {
+            return 1;
+        }
+        int fact_nm1 = calcfactorial(n-1);
+        int fact_n = n * fact_nm1;
+        return fact_n;
+    }
+    public static void main(String args[]) {
+        int n = 5;
+        int ans = calcfactorial(n);
+        System.out.println(ans);
+    }
+}

Fibonacci.java

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+import java.util.*;
+
+public class Fibonacci {
+    public static int printFibonacci(int n) {
+        if (n == 0) {
+            return 0;
+        } else if (n == 1) {
+            return 1;
+        } else {
+            int a = 0, b = 1, result = 0;
+            for (int i = 2; i <= n; i++) {
+                result = a + b;
+                a = b;
+                b = result;
+            }
+            return result;
+        }
+    }
+    public static void main(String args[]) {
+        Scanner sc = new Scanner(System.in);
+        System.out.print("Enter the number of terms in the fibonacci series : ");
+        int n = sc.nextInt();
+        System.out.println("Fibonacci series up to " + n + " terms : ");
+        for (int i = 0; i <n; i++) {
+            System.out.print(printFibonacci(i) + " ");
+        }
+        sc.close();
+    }
+}

FibonacciByRecursion.java

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+public class FibonacciByRecursion {
+    public static void printFib(int a, int b, int n) {
+        if (n == 0) {
+            return;
+        }
+        int c = a + b;
+        System.out.println(c);
+        printFib(b, c, n - 1);
+    }
+    public static void main(String args[]) {
+        int a = 0, b = 1;
+        System.out.println(a);
+        System.out.println(b);
+        int n = 7;
+        printFib(a, b, n - 2);
+    }
+}