Java之冒泡排序和快速排序

冒泡排序

public class bubbleSort {

	public static void main(String[] args) {
		int n = 5;
		int[] a = new int[n];
		for(int i=0;i<a.length;i++) {
			a[i]=new Random().nextInt(100);
		}
		System.out.println(Arrays.toString(a));
		bubbleSort(a);
		
		ArrayList<Character> suiJi = suiJi();
		System.out.println(suiJi);
		
		java.util.Collections.sort(suiJi);
		System.out.println(suiJi);
		
	}


	private static ArrayList<Character> suiJi() {
		ArrayList<Character> list = new ArrayList<>();
		for(int i=0;i<5;i++) {
			String chars = "abcdefghijklmnopqrstuvwxyz";
			list.add(chars.charAt((int)(Math.random() * 26)));
		}
		
		return list;
	}

	private static void bubbleSort(int[] a) {
		for(int i=1;i<a.length;i++) { //相邻数字对比次数
			for(int j=0;j<a.length-i;j++) { //下标递增
				if(a[j]>a[j+1]) {
					int tmp = a[j];
					a[j] = a[j+1];
					a[j+1] = tmp;
				}
			}
		}
		System.out.println(Arrays.toString(a));
	}
}

快速排序

public class QuickSort01 {

	public static void main(String[] args) {

		int[] a = new int[6];
		for (int i = 0; i < a.length; i++) {
			a[i] = new Random().nextInt(100);
		}
		System.out.println(Arrays.toString(a));

		sort(a, 0, a.length - 1);
		System.out.println(Arrays.toString(a));
	}

	private static void sort(int[] a, int lowIndex, int highIndex) {

		int low = lowIndex;
		int high = highIndex;
		
		if (low < high) {
			int pivot = a[low];

			while (low < high) {
				while (a[high] >= pivot && low < high) {
					high--;
				}
				a[low] = a[high];

				while (a[low] < pivot && low < high) {
					low++;
				}
				a[high] = a[low];
			}
			a[low] = pivot;
			
			System.out.println(lowIndex);
			System.out.println(highIndex);

			//快速排序低位  或  高位每次递归都是变化的，所以每次递归要重新赋值给方法内部的新low和新high
			sort(a, lowIndex, low - 1);		
			sort(a, low + 1, highIndex);

		}
	}
}