排序算法小記

/**
	 * 冒泡
	 * 
	 * @param a
	 * @param length
	 */
	public void bubbleSort(int a[], int length) {
		System.out.println("---------冒泡排序---------");
		int x;

		// i從0開始,所以i+j和i+j+1比較，j小於length - 1 - i
		for (int i = 0; i < length - 1; i++) {
			for (int j = 0; j < length - 1 - i; j++) {
				if (a[i + j] > a[i + j + 1]) {
					x = a[i + j];
					a[i + j] = a[i + j + 1];
					a[i + j + 1] = x;
				}
			}
			System.out.println(i + "  " + Arrays.toString(a));
		}

		// i從1開始,所以i+j和i+j-1比較，j小於length - i
		for (int i = 1; i < length; i++) {
			for (int j = 1; j < length - i; j++) {
				if (a[i + j] < a[i + j - 1]) {
					x = a[i + j];
					a[i + j] = a[i + j - 1];
					a[i + j - 1] = x;
				}
			}
			System.out.println(i + "  " + Arrays.toString(a));
		}
	}

	/**
	 * 直接插入算法
	 * 
	 * @param a
	 */
	public void insertSort(int a[]) {
		System.out.println("---------直接插入---------");
		int temp;// 記錄當前許插入的值
		for (int i = 1; i < a.length; i++) {
			temp = a[i];
			for (int j = i - 1; j >= 0; j--) {
				if (a[j] > temp) {
					a[j + 1] = a[j];
				} else {
					break;
				}
				a[j] = temp;
			}
			System.out.println(i + "  " + Arrays.toString(a));
		}
	}

	/**
	 * 選擇插入
	 * 
	 * @param a
	 */
	public void selectSort(int a[]) {
		System.out.println("---------選擇插入---------");
		int temp;
		for (int i = 0; i < a.length; i++) {
			for (int j = i + 1; j < a.length; j++) {
				temp = a[i];
				if (a[j] < a[i]) {
					a[i] = a[j];
					a[j] = temp;

				}
			}
			System.out.println(i + "  " + Arrays.toString(a));
		}
	}

	/**
	 * 選擇插入
	 * 
	 * @param a
	 */
	public void shellSort(int a[]) {
		System.out.println("---------希爾插入---------");
		int temp;
		int addNum = a.length / 2;
		while (addNum > 0) {
			for (int i = 0; i < a.length; i++) {
				for (int j = i; j < a.length - addNum; j = j + addNum) {
					temp = a[j];
					if (a[j] > a[j + addNum]) {
						a[j] = a[j + addNum];
						a[j + addNum] = temp;

					}
				}
				System.out.println(addNum + "  " + i + "  " + Arrays.toString(a));
			}
			addNum = addNum / 2;
		}
	}