排序算法java实现

内排序和外排序。在排序过程中，全部记录存放在内存，则称为内排序，如果排序过程中需要使用外存，则称为外排序。

　　内排序有可以分为以下几类：

　　(1)、插入排序：直接插入排序、二分法插入排序、希尔排序。

　　(2)、选择排序：简单选择排序、堆排序。

　　(3)、交换排序：冒泡排序、快速排序。

　　(4)、归并排序

　　(5)、基数排序

1.直接插入排序

public class StraitInsertionSort {
    public static void main(String[] args)
    {
        int[] a = {32,4,557,12,76,2,34,56,21,67,88,43};
        for (int i =1;i<a.length;i++)
        {
            int temp = a[i];
            
            int j;
            for(j=i-1;j>=0;j--)
            {
                //将大于temp的往后移一位
                if(a[j]>temp)
                {
                    a[j+1]=a[j];
                }
                else
                {
                    break;
                }
                a[j]=temp;
                
            }

        }
        for (int i = 0; i<a.length;i++)
        {
        System.out.print(a[i]+" ");
        }
    }

}

2.二分法插入排序

public class BinarySort {
    public static void main(String[] args) {
        int[] a = { 12, 54, 23, 7, 96, 32, 4, 62, 21, 97, 23, 123, 564, 99 };
        // 当right<left时，停止查找插入的位置,插入位置为a[left]或a[right+1]
        for (int i = 0; i < a.length; i++) {
            int temp = a[i];
            int left = 0;
            int right = i - 1;
            int mid = 0;
            while (left <= right) {
                mid = (left + right) / 2;
                if (temp < a[mid]) {
                    right = mid - 1;
                } else {
                    left = mid + 1;
                }
            }
            // 插入位置a[left]到a[i-1]之间的数字向后移一位
            for (int j = i - 1; j >= left; j--) {
                a[j + 1] = a[j];
            }
            a[right+1] = temp;

        }
        for (int m = 0; m < a.length; m++) {
            System.out.print(a[m] + " ");
        }

    }

}

3.希尔排序

public class ShellSort {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int[] a ={123,5,21,87,54,87,23,11,3,57,90,75,9};
        //不稳定，两个数字相同会被移动
        int d=a.length;
        while(true)
        {
            d=d/2;
            for(int x=0;x<d;x++)
            {
                for(int i=x+d;i<a.length;i=i+d)
                {
                    int temp=a[i];
                    int j;
                    for(j=i-d;j>=0&&a[j]>temp;j=j-d)
                    {
                        a[j+d]=a[j];
                    }
                    a[j+d]=temp;
                }
            }
            if(d==1)
            {
                break;
            }
        }
        for(int i =0;i<a.length;i++)
        {
            System.out.print(a[i]+" ");
        }
    }

}

4.简单选择排序

public class StraitSelectionSort {
    public static void main(String[] args)
    {
        int[] a={23,5,3,21,88,45,23,455,644,322,456,9};
        for(int i=0;i<a.length;i++)
        {
            int min=a[i];
            int n=i;//最小数的索引
            for(int j=i+1;j<a.length;j++)
            {
                if(a[j]<min)
                {
                    min=a[j];
                    n=j;
                }
            }
            a[n]=a[i];
            a[i]=min;
        }
        for(int i=0;i<a.length;i++)
        {
            System.out.print(a[i]+" ");
        }
    }

}

5.堆排序

import java.util.Arrays;

public class HeapSort {
    public static void main(String[] args)
    {
        int[] a={40,24,64,77,89,3,2,13,75,33,13,54,23,98};
        int arrayLength=a.length;
        for(int i=0;i<arrayLength;i++)
        {
            //建堆
            buildMaxHeap(a,arrayLength-1-i);
            //交换堆顶和最后一个元素
            swap(a,0,arrayLength-1-i);
            System.out.println(Arrays.toString(a));
        }
    }

    //对data数组从0到LastIndex建大顶堆
    public static void buildMaxHeap(int[] data,int lastIndex)
    {
        //从lastIndex的父节点开始
        for(int i=(lastIndex-1)/2;i>=0;i--)
        {
            //k保存正在判断的节点
            int k=i;
            //如果当前k节点的子节点存在
            while(k*2+1<=lastIndex)
            {
                //k节点左子节点的索引
                int biggerIndex=2*k+1;
                //如果biggerIndex小于lastIndex,则biggerIndex+1代表的k的右子节点存在
                if(biggerIndex<lastIndex)
                {
                    //如果右子节点较大
                    if(data[biggerIndex]<data[biggerIndex+1])
                    {
                        //biggerIndex总是记录较大子节点的索引
                        biggerIndex++;
                    }
                }
                //如果k节点的值小于较大子节点的值
                if(data[k]<data[biggerIndex])
                {
                    swap(data,k,biggerIndex);
                    //将biggerIndex赋予k,开始下一次循环
                    k=biggerIndex;
                }
                else
                {
                    break;
                }
            }
        }
    }
    private static void swap(int[] data, int i, int j) {
        // TODO Auto-generated method stub
        int tmp=data[i];
        data[i]=data[j];
        data[j]=tmp;
        
    }
}

6.冒泡排序

public class BubbleSort {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int[] a ={32,54,12,78,95,23,12,65,88,99};
        for(int i=0;i<a.length;i++)
        {
            //遍历一次把最大的沉下去，或把最小的浮上来
            for(int j=a.length-i-1;j>0;j--)
            {
                if(a[j-1]>a[j])
                {
                    int tmp=a[j];
                    a[j]=a[j-1];
                    a[j-1]=tmp;
                }
            }
        }
        for (int i=0;i<a.length;i++)
        {
            System.out.print(a[i]+" ");
        }

    }

}

7.快速排序

public class QuikSort {
    public static void main(String[] args) {
        int[] a = { 32, 5, 6, 7, 341, 12, 567, 84, 234, 99 };
        quik(a);
        for(int i=0;i<a.length;i++)
        {
            System.out.print(a[i]+" ");
        }
    }

    private static void quik(int[] a) {
        if (a.length > 0) {
            quickSort(a, 0, a.length - 1);
        }
    }

    private static void quickSort(int[] a, int low, int high) {
        // TODO Auto-generated method stub
        if (low < high) {
            int mid = getMiddle(a, low, high);
            quickSort(a, low, mid - 1);
            quickSort(a, mid + 1, high);
        }

    }

    private static int getMiddle(int[] a, int low, int high) {
        // TODO Auto-generated method stub
        int tmp = a[low];// 基准元素
        while (low < high) {
            // 找到比基准元素小的元素位置
            while (low < high && a[high] >= tmp) {
                high--;
            }
            a[low] = a[high];
            while (low < high && a[low] < tmp) {
                low++;
            }
            a[high] = a[low];
        }
        a[low] = tmp;
        return low;
    }

}

8.归并排序

public class MergeSort {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int[] a ={12,34,66,8,4,13,76,90,56,11,36};
        mergeSort(a,0,a.length-1);
        for(int i=0;i<a.length;i++)
        {
            System.out.print(a[i]+" ");
        }

    }

    private static void mergeSort(int[] a, int left, int right) {
        // TODO Auto-generated method stub
        if(left<right)
        {
            int middle=(left+right)/2;
            mergeSort(a,left,middle);
            mergeSort(a,middle+1,right);
            merge(a,left,middle,right);
        }
                
    }

    private static void merge(int[] a, int left, int middle, int right) {
        // TODO Auto-generated method stub
        int[] tmpArr=new int[a.length];
        int mid = middle+1;//右边的起始位置
        int tmp=left;
        int third=left;
        while(left<=middle&&mid<=right)
        {
            //从两个数组中取较小的数放入tmpArr
            if(a[left]<=a[mid])
            {
                tmpArr[third++]=a[left++];
            }
            else
            {
                tmpArr[third++]=a[mid++];
            }
        }
        //将剩余部分放入tmpArr
        while(left<=middle)
        {
            tmpArr[third++]=a[left++];
        }
        while(mid<=right)
        {
            tmpArr[third++]=a[mid++];
        }
        while(tmp<=right)
        {
            a[tmp]=tmpArr[tmp++];
        }
        
    }

}

9.基数排序

import java.util.ArrayList;
import java.util.List;

public class BucketSort {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int[] a = { 23, 65, 8, 23, 67, 8, 42, 45, 78, 934, 66, 34 };
        sort(a);
        for (int i = 0; i < a.length; i++) {
            System.out.print(a[i] + " ");
        }

    }

    private static void sort(int[] array) {
        // TODO Auto-generated method stub
        // 找到最大数，确定要排序几遍
        int max = 0;
        for (int i = 0; i < array.length; i++) {
            if (max < array[i]) {
                max = array[i];
            }
        }
        // 判断位数
        int times = 0;
        while (max > 0) {
            max = max / 10;
            times++;
        }
        // 建立十个队列
        List<ArrayList> queue = new ArrayList<ArrayList>();
        for (int i = 0; i < 10; i++) {
            ArrayList queue1 = new ArrayList();
            queue.add(queue1);
        }
        // 进行times次分配和收集
        for (int i = 0; i < times; i++) {
            // 分配
            for (int j = 0; j < array.length; j++) {
                int x = array[j] % (int) Math.pow(10, i + 1) / (int) Math.pow(10, i);
                ArrayList<Integer> queue2 = queue.get(x);
                queue2.add(array[j]);
                queue.set(x, queue2);
            }
            // 收集
            int count = 0;
            for (int j = 0; j < 10; j++) {
                while (queue.get(j).size() > 0) {
                    ArrayList<Integer> queue3 = queue.get(j);
                    array[count] = queue3.get(0);
                    queue3.remove(0);
                    count++;
                }
            }
        }
    }

}

 

参考链接：http://www.cnblogs.com/liuling/p/2013-7-24-01.html