经典排序算法——快速排序

链接：http://www.cnblogs.com/morewindows/archive/2011/08/13/2137415.html

Java代码实现：

public class Sort {
	static final int MAX = 20;

	public static void main(String[] args) {
		int[] data = new int[MAX];
		Random random = new Random();
		// 生成一个随机数组
		for (int i = 0; i < MAX; i++) {
			data[i] = random.nextInt(MAX * MAX);
		}
		// 打印排序前数据内容
		System.out.println(Arrays.toString(data));
		quickSort(data, 0, MAX - 1);
		// 打印排序后的数组
		System.out.println(Arrays.toString(data));
	}

	static void quickSort(int[] data, int p, int q) {
		if (p < q) {
			int r = partition(data, p, q);
			quickSort(data, p, r - 1);
			quickSort(data, r + 1, q);
		}
	}

	static int partition(int[] data, int p, int q) {
		int pvt = q, i = p - 1;
		int temp;
		for (int j = i + 1; j < q; j++) {
			if (data[j] < data[pvt]) {
				temp = data[j];
				data[j] = data[++i];
				data[i] = temp;
			}
		}
		temp = data[++i];
		data[i] = data[pvt];
		data[pvt] = temp;
		return i;
	}
}