Java实现十种排序算法

一、冒泡排序

public static void main(String[] args) {
        // TODO Auto-generated method stub
		boolean flag = false;
		Date date = new Date();
		SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		String dateStr = simpleDateFormat.format(date);
		System.out.println(dateStr);
		int[] arr = { 3, -1, 10, 9, 20 };
		for (int i = 0; i < arr.length - 1; i++) {
			for (int j = 0; j < arr.length - i - 1; j++) {
				if (arr[j] > arr[j + 1]) { 
					flag = true;
					int temp = arr[j];
					arr[j] = arr[j + 1];
					arr[j + 1] = temp;
				}
			}
			if (!flag) {
				break;
			} else {
				flag = false;
			}
		}
		System.out.println(Arrays.toString(arr));
		Date date1 = new Date(); 
		SimpleDateFormat simpleDateFormat1 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); 
		String dateStr1 = simpleDateFormat1.format(date); 
		System.out.println(dateStr1);
}

二、选择排序

public static void main(String[] args) {
		// TODO Auto-generated method stub
		int[] arr = { 3, -1, 10, 9, -2 };
		for (int i = 0; i < arr.length - 1; i++) {
			int min = arr[i];
			int index = i;
			for (int j = i + 1; j < arr.length; j++) {
				if (min > arr[j]) {
					min = arr[j];
					index = j;
				}
			}
			if (index != i) {
				arr[index] = arr[i];
				arr[i] = min;
			}
		}
		System.out.println(Arrays.toString(arr));
}

三、插入排序

public static void main(String[] args) {
		// TODO Auto-generated method stub
		int[] arr = { 3, -1, 10, 9, 2 };
		for (int i = 1; i < arr.length; i++) {
			int insertVal = arr[i];
			int insertIndex = i - 1;
			while (insertIndex >= 0 && arr[insertIndex] > insertVal) {
				arr[insertIndex + 1] = arr[insertIndex];
				insertIndex--;
			}
			arr[insertIndex + 1] = insertVal;
		}
		System.out.println(Arrays.toString(arr));
}

四、希尔排序

public static void main(String[] args) {
		// TODO Auto-generated method stub
        int[] arr = { 3, -1, 10, 9, 20 };
		for (int i = arr.length / 2; i > 0; i /= 2) { 
			for (int j = i; j < arr.length; j++) { 
				for (int k = j - i; k >= 0; k -= i) { 
					if (arr[k] > arr[k + i]) { 
						int temp = arr[k];
						arr[k] = arr[k + i];
						arr[k + i] = temp;
					}
				}
			}
		}
        System.out.println(Arrays.toString(arr));
}

五、归并排序

    public static void main(String[] args) {
		// TODO Auto-generated method stub
		int[] arr = { 3, -1, 10, 9, 20 };    
		int[] temp = new int[arr.length];
		mergesort(arr, 0, arr.length-1, temp);
		System.out.println(Arrays.toString(temp));
    }

	public static void mergesort(int[] arr, int left, int right, int[] temp) { 
		if (left < right) {
			int mid = (left + right) / 2;
			mergesort(arr, left, mid, temp); 
			mergesort(arr, mid + 1, right, temp); 
			mergeSort(arr, left, mid, right, temp); 
		}
	}

	public static void mergeSort(int[] arr, int left, int mid, int right, int[] temp) {
		int i = left; 
		int j = mid + 1; 
		int t = 0; 

		while (i <= mid && j <= right) {
			if (arr[i] <= arr[j]) {
				temp[t] = arr[i];
				i += 1;
				t += 1;
			} else {
				temp[t] = arr[j];
				j += 1;
				t += 1;
			}
		}
		while (i <= mid) {
			temp[t] = arr[i];
			t += 1;
			i += 1;
		}
		while (j <= right) {
			temp[t] = arr[j];
			t += 1;
			j += 1;
		}
		t = 0;
		int tempLeft = left;
		while (tempLeft <= right) {
			arr[tempLeft] = temp[t];
			tempLeft += 1;
			t += 1;
		}
	}

六、快速排序

    public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();

		int[] arr = new int[n];

		for (int i = 0; i < n; i++) {
			arr[i] = sc.nextInt();
		}
		quickSort(arr, 0, arr.length - 1);
		System.out.println(Arrays.toString(arr));
	}

	public static void quickSort(int[] arr, int left, int right) {
		int l = left;
		int r = right;
		int pivot = arr[(left + right) / 2];
		while (l < r) {
			while (arr[l] < pivot) {
				l += 1;
			}
			while (arr[r] > pivot) {
				r -= 1;
			}
			if (l >= r) {
				break;
			}
			int temp = arr[l];
			arr[l] = arr[r];
			arr[r] = temp;
			if (arr[l] == pivot) {
				r -= 1;
			}
			if (arr[r] == pivot) {
				l += 1;
			}
		}
		if (l == r) {
			l += 1;
			r -= 1;
		}
		if (left < r) {
			quickSort(arr, left, r);
		}
		if (right > l) {
			quickSort(arr, l, right);
		}

	}

七、堆排序

    public static void main(String[] args) {

		int[] arr = { 2, 1, 7, 6, -1, 5 };

		Date date = new Date();
		SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		String dateStr = simpleDateFormat.format(date);
		System.out.println(dateStr);

		heapSort(arr);

		Date date1 = new Date(); 
		SimpleDateFormat simpleDateFormat1 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		String dateStr1 = simpleDateFormat1.format(date); 
		System.out.println(dateStr1);
		System.out.println(Arrays.toString(arr));
	}

	public static void heapSort(int[] arr) {
		for (int i = arr.length / 2 - 1; i >= 0; i--) {
			adjustHeap(arr, i, arr.length);
		}
		for (int j = arr.length - 1; j > 0; j--) {
			int temp = arr[j];
			arr[j] = arr[0];
			arr[0] = temp;
			adjustHeap(arr, 0, j);
		}
	}

	public static void adjustHeap(int[] arr, int i, int length) {
		int temp = arr[i];
		for (int j = i * 2 + 1; j < length; j = j * 2 + 1) {
			if (j + 1 < length && arr[j] < arr[j + 1]) {
				j++;
			}
			if (arr[j] > temp) {
				arr[i] = arr[j];
				i = j;
			} else {
				break;
			}
		}
		arr[i] = temp;
	}

八、计数排序

public static void main(String[] args) {
		int a[] = { 100, 93, 97, 92, 96, 99, 92, 89, 93, 97, 90, 94, 92, 95 };
		int b[] = countSort(a);
		for (int i : b) {
			System.out.print(i + " ");
		}
		System.out.println();
	}

	public static int[] countSort(int[] a) {
		int b[] = new int[a.length];
		int max = a[0], min = a[0];
		for (int i : a) {
			if (i > max) {
				max = i;
			}
			if (i < min) {
				min = i;
			}
		}
		int k = max - min + 1;
		int c[] = new int[k];
		for (int i = 0; i < a.length; ++i) {
			c[a[i] - min] += 1;
		}
		for (int i = 1; i < c.length; ++i) {
			c[i] = c[i] + c[i - 1];
		}
		for (int i = a.length - 1; i >= 0; --i) {
			b[--c[a[i] - min]] = a[i];
		}
		return b;
	}

九、桶排序

public static void main(String[] args) {

		int[] arr = { 3, 1, 10, 9, 20 };
		bucketSort(arr);

		for (int i : arr) {
			System.out.print(i + " ");
		}

	}

	public static void bucketSort(int arr[])
	{
		int n = arr.length;
		int bask[][] = new int[10][n];
		int index[] = new int[10];
		int max = Integer.MIN_VALUE;
		for (int i = 0; i < n; i++) {
			max = max > (Integer.toString(arr[i]).length()) ? max : (Integer.toString(arr[i]).length());
		}
		String str;
		for (int i = max - 1; i >= 0; i--) {
			for (int j = 0; j < n; j++) {
				str = "";
				if (Integer.toString(arr[j]).length() < max) {
					for (int k = 0; k < max - Integer.toString(arr[j]).length(); k++)
						str += "0";
				}
				str += Integer.toString(arr[j]);
				bask[str.charAt(i) - '0'][index[str.charAt(i) - '0']++] = arr[j];
			}
			int pos = 0;
			for (int j = 0; j < 10; j++) {
				for (int k = 0; k < index[j]; k++) {
					arr[pos++] = bask[j][k];
				}
				index[j] = 0;
			}
		}
	}

十、基数排序

public static void main(String[] args) {
		// TODO Auto-generated method stub
		int[] arr = { 3, 1, 10, 9, 20 }; 
		radixSort(arr);
		System.out.println(Arrays.toString(arr));
	}

	public static void radixSort(int[] arr) {
		int max = arr[0];
		for (int i = 1; i < arr.length; i++) {
			if (arr[i] > max) {
				max = arr[i];
			}
		}
		int maxLength = (max + "").length();
		
		int[][] bucket = new int[10][arr.length];
		int[] bucketElementCounts = new int[10];

		for (int i = 0, n = 1; i < maxLength; i++, n *= 10) {
			for (int j = 0; j < arr.length; j++) {
				int digitOfElement = arr[j] / n % 10; 
				bucket[digitOfElement ][bucketElementCounts[digitOfElement]] = arr[j]; 
				bucketElementCounts[digitOfElement]++; 
			}

			int index = 0;
			for (int k = 0; k < bucketElementCounts.length; k++) {
				if (bucketElementCounts[k] != 0) {
					for (int l = 0; l < bucketElementCounts[k]; l++) { 
						arr[index++] = bucket[k][l];
					}
				}
				bucketElementCounts[k] = 0; 
			}
		}
	}