快速排序

public class QuickSort {
	public static void main(String[] args) {
		int[] array = { 1, 4, 5, 7, 81, 23, 4, 46, 67, 98, 64, 33, 37, 99,
				111, 23, 3, 298 };

		System.out.println("Before sort:");
		QuickSort.printArray(array);

		quickSort(array);

		System.out.println("After sort:");
		QuickSort.printArray(array);
	}

	public static void quickSort(int[] array) {
		subQuickSort(array, 0, array.length - 1);
	}

	private static void subQuickSort(int[] array, int start, int end) {
		if (array == null || (end - start + 1) < 2) {
			return;
		}

		int part = partition(array, start, end);

		if (part == start) {
			subQuickSort(array, part + 1, end);
		} else if (part == end) {
			subQuickSort(array, start, part - 1);
		} else {
			subQuickSort(array, start, part - 1);
			subQuickSort(array, part + 1, end);
		}
	}

	private static int partition(int[] array, int start, int end) {
		int value = array[end];
		int index = start - 1;

		for (int i = start; i < end; i++) {
			if (array[i] < value) {
				index++;
				if (index != i) {
					QuickSort.exchangeElements(array, index, i);
				}
			}
		}

		if ((index + 1) != end) {
			QuickSort.exchangeElements(array, index + 1, end);
		}

		return index + 1;
	}

	public static void printArray(int[] array) {
		System.out.print("{");
		for (int i = 0; i < array.length; i++) {
			System.out.print(array[i]);
			if (i < array.length - 1) {
				System.out.print(", ");
			}
		}
		System.out.println("}");
	}

	public static void exchangeElements(int[] array, int index1, int index2) {
		int temp = array[index1];
		array[index1] = array[index2];
		array[index2] = temp;
	}
}