Java Program to find number of times sorted array has been rotated

Sample Program:-

public class SampleProgram {  
      public static void main(String[] args) {  
           int ar[] = { 4, 1, 2, 3 };  
           for (int i = 0; i < ar.length; i++) {  
                if (i + 1 == ar.length) {  
                     System.out.println("Array is not rotated");  
                } else {  
                     if (ar[i] > ar[i + 1]) {  
                          System.out.println("Array has been rotated by " + (i + 1) + " position");  
                          break;  
                     }  
                }  
           }  
      }  
 }  

Output:-

Array has been rotated by 1 position  

Enjoy Coding.

Java Program to sort Binary Array

Sample Program:-

public class SampleProgram {  
      public static void main(String[] args) {  
           int ar[] = { 1, 0, 1, 1, 0, 1, 0, 1 };  
           System.out.print("Before sorting : ");  
           for (int n : ar)  
                System.out.print(n);  
           int i = 0, j = ar.length - 1;  
           while (i < j) {  
                if (ar[i] > ar[j]) {  
                     ar[i] = 0;  
                     ar[j] = 1;  
                     i++;  
                     j--;  
                }  
                else if (ar[i] == 0 && ar[j] == 0) {  
                     i++;  
                }  
                else if (ar[i] == 1 && ar[j] == 1) {  
                     j--;  
                }  
                else if (ar[i] < ar[j]) {  
                     i++;  
                     j--;  
                }  
           }  
           System.out.print("\nAfter sorting : ");  
           for (int n : ar)  
                System.out.print(n);  
      }  
 }  

Output:-

Before sorting : 10110101  
 After sorting : 00011111  

Enjoy Coding.

Java program to change case in String

Sample Program:-

 public class SampleProgram {  
      public static void main(String[] args) {  
           String s = "inSeRt";  
           char ar[] = s.toCharArray();  
           for (int i = 0; i < ar.length; i++) {  
                if (ar[i] >= 65 && ar[i] <= 90) { // convert upperCase to lowerCase  
                     ar[i] += 32;  
                } else if (ar[i] >= 97 && ar[i] <= 122) { // convert lowerCase to  
                                                                       // upperCase.  
                     ar[i] -= 32;  
                }  
           }  
           System.out.println(new String(ar));  
      }  
 }  

Output:-

INsErT  

Enjoy Coding.

Java Program to find all duplicate elements in List

Sample Program:-

 import java.util.ArrayList;  
 import java.util.List;  
 public class SampleProgram {  
      public static void main(String[] args) {  
           List<Integer> list = new ArrayList<Integer>();  
           list.add(1);  
           list.add(2);  
           list.add(5);  
           list.add(3);  
           list.add(3);  
           list.add(1);  
           list.add(7);  
           System.out.println("Original list: " + list);  
           List<Integer> newList = new ArrayList<Integer>();  
           System.out.print("Duplicate numbers in list are: ");  
           for (int i : list) {  
                if (newList.contains(i))  
                     System.out.print(i + " ");  
                else  
                     newList.add(i);  
           }  
      }  
 }  

Output:-

 Original list: [1, 2, 5, 3, 3, 1, 7]  
 Duplicate numbers in list are: 3 1   

Enjoy Coding.

Find index in an array such that sum of left elements is equal to sum of right in Java

Sample Program:-

 public class SampleProgram {  
      public static void main(String[] args) {  
           int ar[] = { 2, 4, 4, 1, 1 };  
           int leftIndex = 0, rightIndex = ar.length - 1;  
           int leftSum = 0, rightSum = 0;  
           while (leftIndex <= rightIndex) {  
                if (leftSum > rightSum)  
                     rightSum = rightSum + ar[rightIndex--];  
                else  
                     leftSum = leftSum + ar[leftIndex++];  
           }  
           if (leftSum == rightSum)  
                System.out.println("Index is:" + (rightIndex + 1));  
           else  
                System.out.println("index Not Found");  
      }  
 }  

Output:-

Index is:2  

Enjoy Coding.

Java Program to find largest of Three Numbers

Sample Program:-

 public class LargestNumber {  
      public static void main(String[] args) {  
           int a, b, c;  
           a = 20;  
           b = 30;  
           c = 40;  
           if (a > b && a > c)  
                System.out.println("a is largest");  
           else if (a < b && b > c)  
                System.out.println("b is largest");  
           else if (a < c && b < c)  
                System.out.println("c is largest");  
           else  
                System.out.println("a, b, c are not different");  
      }  
 }  

Output:-

 c is largest  

Enjoy Coding.

Java Program to convert Decimal into Binary

Sample Program:-

 public class DecimalToBinary {  
      public static void main(String[] args) {  
           int decimal = 14;  
           if (decimal == 0) {  
                System.out.println("0");  
           }  
           String binary = "";  
           while (decimal > 0) {  
                binary = (decimal % 2) + binary;  
                decimal = decimal / 2;  
           }  
           System.out.println("Binary value is:" + binary);  
      }  
 }  

Output:-

Binary value is:1110  

Enjoy Coding.

Java Program to convert binary into decimal

Binary Numbers are represented in the form of 0's and 1's.

For example:-10 is 2 in decimal form

Sample Program:-

public class BinaryToDecimal {  
      public static void main(String[] args) {  
           int binary = 1110;  
           int decimal = 0;  
           int power = 0;  
           while (binary > 0) {  
                decimal += (binary % 10) * Math.pow(2, power++);  
                binary = binary / 10;  
           }  
           System.out.println("Decimal Number is:" + decimal);  
      }  
 }  

Output:-

Decimal Number is:14  

Enjoy Coding.

Find two maximum numbers in array

Sample Program:-

public class MaxtwoNumbers {  
      public static void main(String[] args) {  
           int a[] = { 6, 99, 45, 3, 77 };  
           int max1 = 0;  
           int max2 = 0;  
           for (int i = 0; i < a.length; i++) {  
                if (a[i] > max1) {  
                     max2 = max1;  
                     max1 = a[i];  
                } else if (a[i] > max2) {  
                     max2 = a[i];  
                }  
           }  
           System.out.println("Maximum 2 numbers are:" + max1 + " and " + max2);  
      }  
 }  

Output:-

Maximum 2 numbers are:99 and 77  

Enjoy Coding.

Find sum of all even digits in String

Sample Program:-

public class SumOfAllEven {  
      public static void main(String[] args) {  
           String s = "1j2a3v4a0";  
     char ch[] = s.toCharArray();  
     int sum = 0;  
     for (int i = 0; i < ch.length; i++) {  
         try {  
            int x = Integer.valueOf(String.valueOf(ch[i]));  
            if (x % 2 == 0) {  
               sum += x;  
            }  
         } catch (Exception e) {  
         }  
     }  
     System.out.println(sum);  
      }  
 }  

Output:-

 6  

Explanation:-

Suppose we have String s="java232";
Output for this will be 2+2=4

Enjoy Coding.

Find number is even or odd without using % operator in Java

Sample Program:-

 public class OddOrEven {  
      public static void main(String[] args) {  
           int number = 2;  
           if ((number & 1) == 0)  
                System.out.println("EVEN");  
           else  
                System.out.println("ODD");  
      }  
 }  

Output:-

 EVEN  

Program Logic:-
Binary number consists of only 0's and 1's ,
if last digit is 0, then number is EVEN in java.

if last digit is 1, then number is ODD in java.
For ex:20 is 10100
25 is 11001

Enjoy Coding.

Find Missing numbers between 1 to 100 in sorted array in java

Sample Program:-

 public class MissingNumber {  
      public static void main(String[] args) {  
           int arr[] = { 2, 11, 55, 77, 88, 99 };  
           System.out.println("Given Array: ");  
           for (int j = 0; j < arr.length; j++)  
                System.out.print(arr[j] + " ");  
           System.out.println("\nNumbers missing between 1 to 100 in array:-");  
           int j = 0;  
           for (int i = 1; i <= 100; i++) {  
                if (j < arr.length && i == arr[j])  
                     j++;  
                else  
                     System.out.print(i + " ");  
           }  
      }  
 }  

Output:-


Given Array:
2 11 55 77 88 99
Numbers missing between 1 to 100 in array:-
1 3 4 5 6 7 8 9 10 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 78 79 80 81 82 83 84 85 86 87 89 90 91 92 93 94 95 96 97 98 100

Enjoy Coding.

Difference between Set and List

	List	Set
Insertion Order	List maintains insertion order in which element are added.	Most of the Set implementation does not maintains an insertion order. For ex:HashSet. LinkedHashSet does maintain insertion order. TreeSet are sorted by natural order.
Duplicate	Allows to store duplicate elements in java.	Does not allow duplicate elements.
Null Keys	Allow to store any number of null values.	Most of the Set implementation only allow one null values. Tree Set does not allow any null value.
Implementing Classes	ArrayList,Linkedlist,Vector etc.	HashSet,LinkedHashSet,TreeSet etc.
Structure	List are resizable array.	Set uses map for their internal implementation.
Index based	List are index based structure. Hence element can be retrieved based on index.	Set is not index based collection.

Enjoy Reading.

Java Program to print Reverse pyramid

Pyramid Sample:-

12345
1234
123
12
1

Sample Program:-

public class ReversePyramid {  
      public static void main(String[] args) {  
           for (int i = 5; i > 0; i--) {  
                for (int j = 0; j < i; j++) {  
                     System.out.print(j + 1);  
                }  
                System.out.println("");  
           }  
      }  
 }  

Output:-

 12345  
 1234  
 123  
 12  
 1  

Enjoy Coding.

Java Program to print Pyramid of stars using nested for loops

Pyramid Example:-

*
**
***
****
*****

Sample Program:-

public class JavaPyramid {  
      public static void main(String[] args) {  
           for (int i = 1; i <= 5; i++) {  
                for (int j = 0; j < i; j++) {  
                     System.out.print("*");  
                }  
                System.out.println("");  
           }  
      }  
 }  

Output:-

 *  
 **  
 ***  
 ****  
 *****  

Enjoy Programming.

Java Program to Count all distinct pairs with difference equal to k

Given an integer array and a positive integer k, count all distinct pairs with difference equal to k.

Example:-

arr[]:-{1, 5, 3, 4, 2}, k = 3
Output: 2
2 pairs({1, 4} and {5, 2}) with difference equal to 3.

Sample Program:-

package com.shc.ecom.payment.web.rest;  
 /**  
  * @author sdixit  
  *  
  */  
 public class Example {  
      /**  
       * @param args  
       */  
      public static void main(String[] args) {  
           int arr[] = { 1, 5, 3, 4, 2 };  
           int k = 3;  
           System.out.println("Count of pairs :-" + countPairsWithDiffK(arr, k));  
      }  
      private static int countPairsWithDiffK(int[] arr, int k) {  
           int count = 0;  
           int n = arr.length;  
           for (int i = 0; i < n; i++) {  
                for (int j = i + 1; j < n; j++)  
                     if (arr[i] - arr[j] == k || arr[j] - arr[i] == k)  
                          count++;  
           }  
           return count;  
      }  
 }  

Sample Output:-

 Count of pairs :-2  

Enjoy Programming.