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Author: nsgowebjavaprog

Recursion.java

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+/*
+public class Recursion {
+  public static void print_num(int n){
+       if(n==0){
+           return;
+       }
+       System.out.println(n);
+       print_num(n-1);
+   }
+   public static void main(String[] args) {
+       int n = 5;
+       print_num(n); */
+
+    // 2
+
+   /*
+    public static void print_sum(int i,int n,int sum){
+        if(i == n){
+            sum += i;
+            System.out.println(sum);
+            return;
+        }
+        sum += i;
+        print_sum(i+1,n,sum);
+    }
+    public static void main(String[] args) {
+        print_sum(1,10,0);
+    }
+    */
+
+     // 3
+   /* public static int factorial(int n){
+        if( n==0 || n==1){
+            return 1;
+        }
+        int fact_nm1 = factorial(n-1);
+        int fact_n = n * fact_nm1;
+        return fact_n;
+    }
+
+    public static void main(String[] args) {
+        int n = 5;
+        System.out.println(factorial(n));
+    }*/
+
+    // 4. fib
+
+   /* public static void fib_series(int a,int b,int n){
+        if(n==0){
+            return;
+        }
+        int c=  a+b;
+        System.out.println(c);
+        fib_series(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;
+        fib_series(a,b,n-2);
+    }
+}
+*/
+
+// Tower_Of_Hanoi
+/*
+public class Recursion {
+    public static void Tower_Of_Hanoi(int n,String src, String helper,String dest){
+
+        if(n == 1){
+            System.out.println("Transfer Disk "+n+" From "+src+" To "+dest);
+            return;
+        }
+        Tower_Of_Hanoi(n-1,src,dest,helper);
+        System.out.println("Transfer Disk "+n+" From "+src+" To "+dest);
+        Tower_Of_Hanoi(n-1,helper,src,dest);
+    }
+
+    public static void main(String[] args) {
+        int n =3;
+        Tower_Of_Hanoi(n,"S","H","D");
+    }
+}
+// OUTPUT:
+
+Transfer Disk 1 From S To D
+Transfer Disk 2 From S To H
+Transfer Disk 1 From D To H
+Transfer Disk 3 From S To D
+Transfer Disk 1 From H To S
+Transfer Disk 2 From H To D
+Transfer Disk 1 From S To D
+ */
+
+// 2.reverse string
+
+/*
+public class Recursion {
+    public static void string_rev(String str,int idx){   // TC=O(n)
+        if(idx==0){
+            System.out.print(str.charAt(idx));
+            return;
+        }
+        System.out.print(str.charAt(idx));
+        string_rev(str,idx-1);
+    }
+
+    public static void main(String[] args) {
+        String str = "Apple";
+        string_rev(str,str.length()-1);
+    }
+}*/
+
+
+
+// Hi It A Recursion With Best Solution
+
+// 1.Print Name 'N' Times using Recursion    || TC=O(n)  SC=O(n) ||
+
+/*
+public class Recursion {
+    public static void print_name(int i, int n){
+        if(i>n){
+            return;
+        }
+        System.out.println("NS Loni Good Morning");
+        print_name(i+1,n);
+    }
+
+    public static void main(String[] args) {
+        int n =3;
+        print_name(1,n);
+    }
+}
+// output:
+
+NS Loni Good Morning
+NS Loni Good Morning
+NS Loni Good Morning
+ */
+
+
+// 2. Print linearly From 1 to N
+/*
+public class Recursion {
+    public static void print_name(int i, int n){
+        if(i>n){
+            return;
+        }
+        System.out.print(" "+i);
+        print_name(i+1,n);
+    }
+
+    public static void main(String[] args) {
+        int n =5;
+        print_name(1,n);
+    }
+}
+//OUTPUT:   1 2 3 4 5
+*/
+
+
+
+// 3. Print linearly From N to 1
+/*
+public class Recursion {
+    public static void print_name(int i, int n){
+        if(i<n){
+            return;
+        }
+        System.out.print(" "+i);
+        print_name(i-1,n);
+    }
+
+    public static void main(String[] args) {
+        int i = 5;
+        int n = 1;
+        print_name(i,n);
+    }
+}
+// OUTPUT:  5 4 3 2 1
+ */
+
+// 4. Print linearly From 1 to N  WITH_OUT USING {i+1}
+/*
+public class Recursion {
+    public static void print_name(int i, int n){
+        if(i<1){
+            return;
+        }
+        print_name(i-1,n);
+        System.out.print(" "+i);
+    }
+
+    public static void main(String[] args) {
+        int n =5;
+        print_name(n,n);
+    }
+}*/
+// OUTPUT:  1 2 3 4 5
+
+// 5. Print linearly From n TO 1-->  WITH_OUT USING {i-1}
+/*
+public class Recursion {
+    public static void print_name(int i, int n){
+        if(i>n){
+            return;
+        }
+        print_name(i+1,n);
+        System.out.print(" "+i);
+    }
+
+    public static void main(String[] args) {
+        int n =5;
+        int i=1;
+        print_name(i,n);
+    }
+}*/
+// OUTPUT:  5 4 3 2 1
+
+
+// 6.Sum n natural numbers
+/*
+public class Recursion {
+    public static int sum_n_num(int n){
+        if(n==0){
+            return 0;
+        }
+        return n + sum_n_num(n-1);
+    }
+
+    public static void main(String[] args) {
+        int n = 5;
+        int res = sum_n_num(n);
+        System.out.println(res);
+    }
+}
+// 15
+ */
+
+// 7.Factorial     TC = O(n)
+/*
+public class Recursion {
+    public static int sum_n_num(int n){
+        if(n==1){
+            return 1;
+        }
+        return n * sum_n_num(n-1);
+    }
+
+    public static void main(String[] args) {
+        int n = 5;
+        int res = sum_n_num(n);
+        System.out.println("Factorial of Number: "+res);
+    }
+}
+// output: Factorial of Number: 120
+*/
+
+// 8.Fibonacci Series
+/*
+
+public class Recursion {
+    public static int fibo(int n){
+        if(n==0){
+            return 0;
+        }
+        if(n==1){
+            return 1;
+        }
+        return fibo(n-1) + fibo(n-2);
+    }
+
+    public static void print_fibo(int n){
+        for (int i = 0; i < n; i++) {
+            System.out.print(fibo(i)+"  ");      //   0  1  1  2  3
+        }
+    }
+
+    public static void main(String[] args) {
+        int n = 5;
+        int res = fibo(n);
+        System.out.println("Fib of Numbers: "+res);  // Fib of Numbers: 5
+        print_fibo(n);
+    }
+}
+*/
+
+//  9. Reverse an Array
+/*
+public class Recursion {
+    public static void swap(int arr[],int i, int j){
+        int temp = arr[i];
+        arr[i] = arr[j];
+        arr[j] = temp;
+    }
+    public static void rev_array(int i, int arr[], int n){
+        if(i>=n/2){
+            return;
+        }
+        swap(arr ,i,n-i-1);
+        rev_array(i+1, arr, n);
+    }
+
+    public static void main(String[] args) {
+        int arr[] = {1,2,3,4,5};
+        int n = arr.length;
+        rev_array(0,arr, n);
+        for (int i = 0; i < n; i++) {
+            System.out.print(arr[i]+"  ");            // 5  4  3  2  1
+        }
+    }
+}
+*/
+
+// 10. Palindrome
+/*
+public class Recursion {
+    public static boolean isPalindrome(String str) {
+        return isPalindrome(str, 0, str.length() - 1);
+    }
+
+    private static boolean isPalindrome(String str, int start, int end) {
+        if (start >= end) {
+            return true;
+        }
+        if (str.charAt(start) != str.charAt(end)) {
+            return false;
+        }
+        return isPalindrome(str, start + 1, end - 1);
+    }
+
+    public static void main(String[] args) {
+        String palindrome1 = "madam";
+        boolean isPalindrome1 = isPalindrome(palindrome1);
+        System.out.println(palindrome1 + " is a palindrome: " + isPalindrome1);
+    }
+}
+ */
+//  output: madam is a palindrome: true
+
+// 11.Print all SubSequence
+// Eg{1}: [3,1,2] ==> [],[1],[2],[3],[1,2],[1,3],[3,2],[3,1,2]---->[8]
+/*
+public class Recursion {
+    public static void generateSubSequences(String str, String current, int index) {
+        if (index == str.length()) {
+            System.out.println(current);
+            return;
+        }
+        generateSubSequences(str, current + str.charAt(index), index + 1);
+        generateSubSequences(str, current, index + 1);
+    }
+
+    public static void main(String[] args) {
+        String str = "abc";
+        generateSubSequences(str, "", 0);
+    }
+}
+// OUTPUT:
+
+ abc
+ ab
+ ac
+ a
+ bc
+ b
+ c
+*/
+
+
+
+
+
+
+
+