Java Practice 11

Write a program to implement Selection sort?

1. public class MySelectionSort {
2. 
   
3. public static int[] doSelectionSort(int[] arr){
4. 
   
5. for (int i = 0; i < arr.length - 1; i++)
6. {
7. int index = i;
8. for (int j = i + 1; j < arr.length; j++)
9. if (arr[j] < arr[index])
10. index = j;
11. 
    
12. int smallerNumber = arr[index]; 
13. arr[index] = arr[i];
14. arr[i] = smallerNumber;
15. }
16. return arr;
17. }
18. 
    
19. public static void main(String a[]){
20. 
    
21. int[] arr1 = {10,34,2,56,7,67,88,42};
22. int[] arr2 = doSelectionSort(arr1);
23. for(int i:arr2){
24. System.out.print(i);
25. System.out.print(", ");
26. }
27. }
28. }

Java Practice 10

Write a program to implement Insertion sort?

1. public class InsertionSort
2.  {
3. public static void main(String a[])
4. {
5. int[] arr1 = {10,34,2,56,7,67,88,42};
6. int[] arr2 = doInsertionSort(arr1);
7. for(int i:arr2){
8. System.out.print(i);
9. System.out.print(", ");
10. }
11. }
12. 
    
13. public static int[] doInsertionSort(int[] input){
14. 
    
15. int temp;
16. for (int i = 1; i < input.length; i++) {
17. for(int j = i ; j > 0 ; j--){
18. if(input[j] < input[j-1]){
19. temp = input[j];
20. input[j] = input[j-1];
21. input[j-1] = temp;
22. }
23. }
24. }
25. return input;
26. }
27. }

Java Practice 9

Write a program to implement quick sort?

1. public class QuickSort
2.  {
3. private int array[];
4. private int length;
5. 
   
6. public void sort(int[] inputArr) {
7. 
   
8. if (inputArr == null || inputArr.length == 0) {
9. return;
10. }
11. this.array = inputArr;
12. length = inputArr.length;
13. quickSort(0, length - 1);
14. }
15. 
    
16. private void quickSort(int lowerIndex, int higherIndex) {
17. 
    
18. int i = lowerIndex;
19. int j = higherIndex;
20. // calculate pivot number, I am taking pivot as middle index number
21. int pivot = array[lowerIndex+(higherIndex-lowerIndex)/2];
22. // Divide into two arrays
23. while (i <= j) {
24. /**
25. * In each iteration, we will identify a number from left side which
26. * is greater then the pivot value, and also we will identify a number
27. * from right side which is less then the pivot value. Once the search
28. * is done, then we exchange both numbers.
29. */
30. while (array[i] < pivot) {
31. i++;
32. }
33. while (array[j] > pivot) {
34. j--;
35. }
36. if (i <= j) {
37. exchangeNumbers(i, j);
38. //move index to next position on both sides
39. i++;
40. j--;
41. }
42. }
43. // call quickSort() method recursively
44. if (lowerIndex < j)
45. quickSort(lowerIndex, j);
46. if (i < higherIndex)
47. quickSort(i, higherIndex);
48. }
49. 
    
50. private void exchangeNumbers(int i, int j) {
51. int temp = array[i];
52. array[i] = array[j];
53. array[j] = temp;
54. }
55. 
    
56. public static void main(String a[]){
57. 
    
58. QuickSort sorter = new QuickSort();
59. int[] input = {24,2,45,20,56,75,2,56,99,53,12};
60. sorter.sort(input);
61. for(int i:input){
62. System.out.print(i);
63. System.out.print(" ");
64. }
65. }
66. }

Java Practice 8

Write a program for merge sort?

1. public class MergeSort {
2. private int[] array;
3. private int[] tempMergArr;
4. private int length;
5. public static void main(String a[]){
6. int[] inputArr = {45,23,11,89,77,98,4,28,65,43};
7. MergeSort mms = new MergeSort();
8. mms.sort(inputArr);
9. for(int i:inputArr){
10. System.out.print(i);
11. System.out.print(" ");
12. }
13. }
14. public void sort(int inputArr[]) 
15. {
16. this.array = inputArr;
17. this.length = inputArr.length;
18. this.tempMergArr = new int[length];
19. doMergeSort(0, length - 1);
20. }
21. private void doMergeSort(int lowerIndex, int higherIndex) {
22. 
    
23. if (lowerIndex < higherIndex) {
24. int middle = lowerIndex + (higherIndex - lowerIndex) / 2;
25. // Below step sorts the left side of the array
26. doMergeSort(lowerIndex, middle);
27. // Below step sorts the right side of the array
28. doMergeSort(middle + 1, higherIndex);
29. // Now merge both sides
30. mergeParts(lowerIndex, middle, higherIndex);
31. }
32. }
33. private void mergeParts(int lowerIndex, int middle, int higherIndex) 
34. {
35. for (int i = lowerIndex; i <= higherIndex; i++) {
36. tempMergArr[i] = array[i];
37. }
38. int i = lowerIndex;
39. int j = middle + 1;
40. int k = lowerIndex;
41. while (i <= middle && j <= higherIndex) {
42. if (tempMergArr[i] <= tempMergArr[j]) {
43. array[k] = tempMergArr[i];
44. i++;
45. } else {
46. array[k] = tempMergArr[j];
47. j++;
48. }
49. k++;
50. }
51. while (i <= middle) {
52. array[k] = tempMergArr[i];
53. k++;
54. i++;
55. }
56. 
    
57. }
58. }

Java Practice 7

Write a program for bubble sort?

import java.util.Scanner;
 
class BubbleSort {
  public static void main(String []args) {
    int n, c, d, swap;
    Scanner in = new Scanner(System.in);
 
    System.out.println("Input number of integers to sort");
    n = in.nextInt();
 
    int array[] = new int[n];
 
    System.out.println("Enter " + n + " integers");
 
    for (c = 0; c < n; c++) 
      array[c] = in.nextInt();
 
    for (c = 0; c < ( n - 1 ); c++) {
      for (d = 0; d < n - c - 1; d++) {
        if (array[d] > array[d+1]) /* For descending order use < */
        {
          swap       = array[d];
          array[d]   = array[d+1];
          array[d+1] = swap;
        }
      }
    }
 
    System.out.println("Sorted list of numbers");
 
    for (c = 0; c < n; c++) 
      System.out.println(array[c]);
  }
}

Java Practice 6

Write a program for Binary Search?(input must be in ascending order)

import java.util.Scanner;
 
class BinarySearch 
{
  public static void main(String args[])
  {
    int c, first, last, middle, n, search, array[];
 
    Scanner in = new Scanner(System.in);
    System.out.println("Enter number of elements");
    n = in.nextInt(); 
    array = new int[n];
 
    System.out.println("Enter " + n + " integers");
 
 
    for (c = 0; c < n; c++)
      array[c] = in.nextInt();
 
    System.out.println("Enter value to find");
    search = in.nextInt();
 
    first  = 0;
    last   = n - 1;
    middle = (first + last)/2;
 
    while( first <= last )
    {
      if ( array[middle] < search )
        first = middle + 1;    
      else if ( array[middle] == search ) 
      {
        System.out.println(search + " found at location " + (middle + 1) + ".");
        break;
      }
      else
         last = middle - 1;
 
      middle = (first + last)/2;
   }
   if ( first > last )
      System.out.println(search + " is not present in the list.\n");
  }
}

Java Practice 5

Write a program to print Alphabets?

class Alphabets
{
   public static void main(String args[])
   {
      char ch;
 
      for( ch = 'a' ; ch <= 'z' ; ch++ )
         System.out.println(ch);
   }
}

Java Practice 4

Write a program using If and else conditions?

class Condition {
  public static void main(String[] args) {
    boolean learning = true;
 
    if (learning) {
      System.out.println("Java programmer");
    }
    else {
      System.out.println("What are you doing here?");
    }
  }
}

Java Practice 3

Write a program to print integers?

class Integers {
  public static void main(String[] arguments) {
    int c; //declaring a variable
 
  /* Using for loop to repeat instruction execution */
 
    for (c = 1; c <= 10; c++) {
      System.out.println(c);
    }
  }
}

Java Practice 2

Write a java program to check palindrome number.

import java.util.*;
 
class Palindrome
{
   public static void main(String args[])
   {
      String original, reverse = "";
      Scanner in = new Scanner(System.in);
 
      System.out.println("Enter a string to check if it is a palindrome");
      original = in.nextLine();
 
      int length = original.length();
 
      for ( int i = length - 1; i >= 0; i-- )
         reverse = reverse + original.charAt(i);
 
      if (original.equals(reverse))
         System.out.println("Entered string is a palindrome.");
      else
         System.out.println("Entered string is not a palindrome.");
 
   }
}

Java Practice

Write a program to check the given number is a prime number or not?

1. package basics.java.com; 
2. public class MyPrimeNumCheck 
3. {
4.  public boolean isPrimeNumber(int number)
5. { 
6. for(int i=2; i<=number/2; i++)
7. {
8.  if(number % i == 0)
9. {
10.  return false; 
11. }
12.  } 
13. return true; 
14. } 
15. public static void main(String a[])
16. { 
17. MyPrimeNumCheck mpc = new MyPrimeNumCheck();
18. System.out.println("Is17primenumber?"+mpc.isPrimeNumber(17));
19. System.out.println("Is 19 prime number? "+mpc.isPrimeNumber(19));
20. System.out.println("Is 15 prime number? "+mpc.isPrimeNumber(15));
21.  }
22.  }