01 经典排序算法

Posted 2021-03-03 alichengxuyuan

1 冒泡排序

import java.util.Random;

public class BubbleSort
{
	public static void main(String args[])
	{
		int[] arrays = BubbleSort.createArrays(10);
		bubble(arrays);
		for (int i = 0; i < arrays.length; i++)
		{
			System.out.print(arrays[i]+"	");
		}
	}

	public static int[] createArrays(int length)
	{
		int[] arrays = new int[length];
		Random rd = new Random();
		for (int i = 0; i < arrays.length; i++)
		{
			arrays[i] = rd.nextInt(100);
		}
		return arrays;
	}

	private static void bubble(int[] arrays)
	{
		for (int i = 0; i < arrays.length - 1; i++)
		{
			for (int j = 0; j < arrays.length - i - 1; j++)
			{
				if(arrays[j] > arrays[j + 1])
				{
					int temp = arrays[j];
					arrays[j] = arrays[j + 1];
					arrays[j + 1] = temp;
				}
			}
		}
	}
}

2 选择排序

import java.util.Arrays;
import java.util.Random;

public class SelectSort
{

	public static void main(String[] args)
	{
		int[] array = SelectSort.createArrays(10);
		select(array);
		System.out.println(Arrays.toString(array));
	}

	private static void select(int[] array)
	{
		int temp;
		for (int i = 0; i < array.length - 1; i++)
		{
			for (int j = i + 1; j < array.length; j++)
			{
				if(array[i] > array[j])
				{
					temp = array[i];
					array[i] = array[j];
					array[j] = temp;
				}
			}
		}
	}

	public static int[] createArrays(int length)
	{
		int[] arrays = new int[length];
		Random rd = new Random();
		for (int i = 0; i < arrays.length; i++)
		{
			arrays[i] = rd.nextInt(100);
		}
		return arrays;
	}
}

3 插入排序

import java.util.Arrays;
import java.util.Random;

public class InsertSort
{
	public static int[] createArrays(int length)
	{
		int[] arrays = new int[length];
		Random rd = new Random();
		for (int i = 0; i < arrays.length; i++)
		{
			arrays[i] = rd.nextInt(100);
		}
		return arrays;
	}

	public static void main(String[] args)
	{
		int[] arrays = InsertSort.createArrays(10);
		insert(arrays);
		System.out.println(Arrays.toString(arrays));
	}

	private static void insert(int[] arrays)
	{
		for (int i = 1; i < arrays.length; i++)
		{
			for (int j = i; j > 0; j--)
			{
				if(arrays[j] > arrays[j - 1])
				{
					int temp = arrays[j];
					arrays[j] = arrays[j - 1];
					arrays[j - 1] = temp;

				}
			}
		}
	}
}

4 快速排序

import java.util.Arrays;
import java.util.Random;

public class QuickSort
{
	public static void main(String args[])
	{
		int[] array = createArrays(10);
		quickSort(array, 0, array.length - 1);
		System.out.println(Arrays.toString(array));
	}

	public static int[] createArrays(int length)
	{
		int[] arrays = new int[length];
		Random rd = new Random();
		for (int i = 0; i < arrays.length; i++)
		{
			arrays[i] = rd.nextInt(100);
		}
		return arrays;
	}

	public static void quickSort(int array[], int low, int high)
	{
		if(low < high)
		{
			int mid = getMid(array, low, high);
			quickSort(array, low, mid - 1);
			quickSort(array, mid + 1, high);
		}
	}

	public static int getMid(int array[], int low, int high)
	{
		int temp = array[low];
		while (low < high)
		{
			while (low < high && temp <= array[high])
			{
				high--;
			}

			array[low] = array[high];

			while (array[low] <= temp && low < high)
			{
				low++;
			}
			array[high] = array[low];
		}
		array[low] = temp;

		return low;
	}
}