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| 1 | +/** |
| 2 | + * |
| 3 | + * @author Varun Upadhyay (https://github.com/varunu28) |
| 4 | + * |
| 5 | + */ |
| 6 | + |
| 7 | +class QuickSort { |
| 8 | + |
| 9 | + /** |
| 10 | + * This method implements the Generic Quick Sort |
| 11 | + * |
| 12 | + * @param array The array to be sorted |
| 13 | + * @param start The first index of an array |
| 14 | + * @param end The last index of an array |
| 15 | + * Sorts the array in increasing order |
| 16 | + **/ |
| 17 | + |
| 18 | + public static <T extends Comparable<T>> void QS(T array[], int start, int end) { |
| 19 | + if (start < end) { |
| 20 | + int PIndex = partition(array, start, end); |
| 21 | + QS(array, start, PIndex - 1); |
| 22 | + QS(array, PIndex + 1, end); |
| 23 | + } |
| 24 | + } |
| 25 | + |
| 26 | + /** |
| 27 | + * This method finds the partition index for an array |
| 28 | + * |
| 29 | + * @param array The array to be sorted |
| 30 | + * @param start The first index of an array |
| 31 | + * @param end The last index of an array |
| 32 | + * Finds the partition index of an array |
| 33 | + **/ |
| 34 | + |
| 35 | + public static <T extends Comparable<T>> int partition(T array[], int start, int end) { |
| 36 | + T pivot = array[end]; |
| 37 | + int PIndex = start; |
| 38 | + for (int i=start;i<end;i++) { |
| 39 | + if (array[i].compareTo(pivot) <= 0) { |
| 40 | + swap(array, i, PIndex); |
| 41 | + PIndex++; |
| 42 | + } |
| 43 | + } |
| 44 | + swap(array, PIndex, end); |
| 45 | + return PIndex; |
| 46 | + } |
| 47 | + |
| 48 | + /** |
| 49 | + * This method swaps two elements of an array |
| 50 | + * |
| 51 | + * @param array The array to be sorted |
| 52 | + * @param initial The first element |
| 53 | + * @param fin The second element |
| 54 | + * Swaps initial and fin element |
| 55 | + **/ |
| 56 | + |
| 57 | + public static <T extends Comparable<T>> void swap(T[] array, int initial, int fin) { |
| 58 | + T temp = array[initial]; |
| 59 | + array[initial] = array[fin]; |
| 60 | + array[fin] = temp; |
| 61 | + } |
| 62 | + |
| 63 | + // Driver Program |
| 64 | + public static void main(String[] args) { |
| 65 | + |
| 66 | + // For integer input |
| 67 | + int[] arr = {3,4,1,32,0,2,44,111,5}; |
| 68 | + Integer[] array = new Integer[arr.length]; |
| 69 | + for (int i=0;i<arr.length;i++) { |
| 70 | + array[i] = arr[i]; |
| 71 | + } |
| 72 | + |
| 73 | + QS(array, 0, arr.length-1); |
| 74 | + |
| 75 | + //Output => 0 1 2 3 4 5 32 44 111 |
| 76 | + for (int i=0;i<array.length;i++) { |
| 77 | + System.out.print(array[i] + " "); |
| 78 | + } |
| 79 | + System.out.println(); |
| 80 | + |
| 81 | + // String Input |
| 82 | + String[] array1 = {"c", "a", "e", "b","d"}; |
| 83 | + |
| 84 | + QS(array1, 0,array1.length-1); |
| 85 | + |
| 86 | + //Output => a b c d e |
| 87 | + for(int i=0; i<array1.length; i++) |
| 88 | + { |
| 89 | + System.out.print(array1[i]+"\t"); |
| 90 | + } |
| 91 | + } |
| 92 | +} |
| 93 | + |
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