01d699924e
Change to List<E> for any type of array. Change value of pivot to value of middle index of unsorted array.
108 lines
2.7 KiB
Java
108 lines
2.7 KiB
Java
/**
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*
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* @author Varun Upadhyay (https://github.com/varunu28)
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*
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*/
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class QuickSort {
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/**
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* This method implements the Generic Quick Sort
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*
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* @param array The array to be sorted
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* @param start The first index of an array
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* @param end The last index of an array
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* Sorts the array in increasing order
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**/
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public static <T extends Comparable<T>> void QS(List<T> list, int left, int right) {
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if (left>=right) { return }
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else
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{
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int pivot = partition(array, left,right);
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QS(list, left, pivot- 1);
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QS(list, pivot + 1, right);
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}
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}
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/**
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* This method finds the partition index for an array
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*
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* @param array The array to be sorted
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* @param start The first index of an array
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* @param end The last index of an array
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* Finds the partition index of an array
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**/
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public static <T extends Comparable<T>> int partition(List<T> list, int left, int right) {
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int mid=(left+right)/2;
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T pivot=list.get(mid);
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swap(list,mid,right);
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while(left<right)
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{
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while(left<right && pivot.compareTo(list.get(left))>=0)
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{
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++left;
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}
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if(left<right)
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{
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swap(list,left,right);
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--right;
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}
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while(left<right && list.get(right).compareTo(pivot)>=0)
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{
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--right;
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}
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if(left<right)
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{
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swap(list,left,right);
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++left;
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}
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}
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return left;
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}
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/**
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* This method swaps two elements of an array
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*
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* @param array The array to be sorted
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* @param initial The first element
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* @param fin The second element
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* Swaps initial and fin element
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**/
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public static <T extends Comparable<T>> void swap(List<E> list, int initial, int fin) {
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E temp= list.get(initial);
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list.set(initial,list.get(fin));
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list.set(fin,temp);
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}
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// Driver Program
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public static void main(String[] args) {
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// For integer input
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ArrayList<Integer> array = new ArrayList<Integer>(9);
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array = {3,4,1,32,0,2,44,111,5};
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QS(array, 0, array.size()-1);
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//Output => 0 1 2 3 4 5 32 44 111
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for (int i=0;i<array.size();i++) {
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System.out.print(array.get(i) + " ");
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}
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System.out.println();
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ArrayList<String> array1=new ArrayList<String>(5);
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array1 = {"c", "a", "e", "b","d"};
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QS(array1, 0,array1.size()-1);
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//Output => a b c d e
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for(int i=0; i<array1.size(); i++)
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{
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System.out.print(array1.get(i)+"\t");
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}
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}
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}
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