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- /**
- * Nate Wheeler
- * hw 17
- * compsci220
- * dec 2, 2015
- * nrwheeler@student.scc.edu
- *
- */
- public class QuickSort2 {
- public static void quickSort(int[] list) {
- quickSort(list, 0, list.length - 1);
- }
- private static void quickSort(int[] list, int first, int last) {
- if (last > first) {
- int pivotIndex = partition(list, first, last);
- quickSort(list, first, pivotIndex - 1);
- quickSort(list, pivotIndex + 1, last);
- }
- }
- //private static int medianOf3(int middle, int first, int last)
- /** Partition the array list[first..last] */
- private static int partition(int[] list, int first, int last) {
- int middle= list[(first+last)/2];
- int pivot; // Choose the first element as the pivot\
- if(first<middle && middle<last)
- pivot=middle;
- if(first<last && middle>last)
- pivot=last;
- else
- pivot=first;
- int low = first; // Index for forward search
- int high = last; // Index for backward search
- while (high > low) {
- // Search forward from left
- while (low <= high && list[low] <= pivot)
- low++;
- // Search backward from right
- while (low <= high && list[high] > pivot)
- high--;
- // Swap two elements in the list
- if (high > low) {
- int temp = list[high];
- list[high] = list[low];
- list[low] = temp;
- }
- }
- while (high > first && list[high] >= pivot)
- high--;
- // Swap pivot with list[high]
- if (pivot > list[high]) {
- list[first] = list[high];
- list[high] = pivot;
- return high;
- }
- else {
- return first;
- }
- }
- /** A test method */
- public static void main(String[] args) {
- int[] list = {2, 3, 2, 5, 6, 1, -2, 3, 14, 12};
- quickSort(list);
- for (int i = 0; i < list.length; i++)
- System.out.print(list[i] + " ");
- }
- }
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