排序

排序的方法有很多种:下面实现冒泡法排序,选择法排序,插入法排序,归并排序,希尔排序,快速排序

package org.exam.order;import org.junit.Test;/** * Created by xin on 15.10.23. */public class App {    private int[] arr={31,23,34,78,26,29,25,41,39,27};    public void display(){        for (int i = 0; i <arr.length ; i++) {            System.out.print(arr[i]+" ");        }        System.out.println();    }    private void swap(int one, int two) {        int temp = arr[one];        arr[one] = arr[two];        arr[two] = temp;    }    //-----------bubbleSort start----------------------    public void bubbleSort() {        for (int out = arr.length - 1; out > 1; out--) {            for (int in = 0; in < out; in++) {                if (arr[in] > arr[in + 1]) {                    swap(in, in + 1);                }            }        }    }    //-----------bubbleSort end------------------------    //-----------selectionSort start----------------------    public void selectionSort() {        int out, in, min;        for (out = 0; out < arr.length - 1; out++) {            min = out;            for (in = out + 1; in < arr.length; in++) {                if (arr[in] < arr[min]) {                    min = in;                }            }            swap(out, min);        }    }    //-----------selectionSort end------------------------    //-----------insertSort start----------------------    public void insertSort(){        for (int out = 1; out < arr.length; out++) {            int tmp= arr[out];//要插入的项，从第二项开始插入            int in=out-1;            while (in>=0&& arr[in]>tmp){//项数比较大时，可考虑用二分法找到插入位置                arr[in+1]= arr[in];                in--;            }            arr[in+1]=tmp;        }    }    //-----------insertSort end------------------------    //-----------recMergeSort start----------------------    private void recMergeSort(int[] workSpace, int lower, int upper) {        if (lower==upper){            return;        }else{            int mid=(lower+upper)/2;            recMergeSort(workSpace,lower,mid);            recMergeSort(workSpace,mid+1,upper);            merge(workSpace,lower,upper);        }    }    private void merge(int[] workSpace,int lower, int upper) {        int mid=(lower+upper)/2,size = upper-lower+1;        int cur = 0,curA = lower,curB= mid+1;        while(curA <= mid && curB <= upper) {            if (arr[curA] < arr[curB]) {                workSpace[cur++] = arr[curA++];            }else {                workSpace[cur++] = arr[curB++];            }        }        while(curA <= mid) {            workSpace[cur++] = arr[curA++];        }        while(curB <= upper) {            workSpace[cur++] = arr[curB++];        }        //已经在workSpace前面部分排好序,复制过来覆盖        for(int i=0; i<size; i++) {            arr[lower + i] = workSpace[i];        }    }    //-----------recMergeSort end------------------------    //-----------shellSort start----------------------    public void shellSort() {        int tmp;        int h = 1;        while (h <= arr.length / 3) {            h = 3 * h + 1;        }        while (h > 0) {            /**             * 假设h=4,arr为14个数的数组(下标从0开始),此程序并不是按(arr[0],arr[4],arr[8],arr[12]),(arr[1],arr[5],arr[9],arr[13]),(arr[2],arr[6],arr[10]),(arr[3],arr[7],arr[11])进行的，             * 当i=4时,可认为只有a[0]一个元素这一组的基础上插入a[4],同理当i=5时,可认为只有a[1]一个元素这一组的基础上插入a[5],同理当i=6时,可认为只有a[2]一个元素这一组的基础上插入a[6],同理当i=7时,可认为只有a[3]一个元素这一组的基础上插入a[7]             * 直至当i=8时，可认为有(arr[0],arr[4])的基础上插入a[8],并且arr[0]与arr[4]是有序的.同理当i=9时，可认为有(arr[1],arr[5])的基础上插入a[9],并且arr[1]与arr[5]是有序的...             * 直至i=12时，可认为有(arr[0],arr[4],a[8])的基础上插入a[12],并且arr[0],arr[4],a[8]是有序的...             */            for (int i = h; i < arr.length; i++) {//当h=1时,此层for为基本的插入法排序                tmp = arr[i];                int j = i;                while (j > h - 1 && arr[j - h] > tmp) {                    arr[j] = arr[j - h];                    j -= h;                }                arr[j] = tmp;            }            h = (h - 1) / 3;        }    }    //-----------shellSort end------------------------    //-----------quickSort start----------------------    public void quickSort(int left,int right){        int size=right-left+1;        if (size<10){//由于中值划分至少有4个项,所以当size>3时,不到走向这个else.当项数小于10时,采用插入法替代是更好的选择.            insertSort(left, right);        }else{            int pivot=medianOf3(left,right);            int position=partition(left,right,pivot);            quickSort(left, position - 1);            quickSort(position + 1, right);        }    }    private int partition(int left,int right,int pivot){        int leftPtr=left;//经过medianOf3排序,组最左项会不大于pivot,所以最初左指针应指向left        int rightPtr=right-1;//经过medianOf3排序,组最右项会不小于pivot,再有right-1为pivot,所以最初右指针应指向right-1        while (true){            while (arr[++leftPtr]<pivot){            }            while (arr[--rightPtr]>pivot){            }            if (leftPtr>=rightPtr){                break;            }else{                swap(leftPtr,rightPtr);            }        }        swap(leftPtr,right-1);//将pivot移至leftPtr,并返回其位置        return leftPtr;    }    private void insertSort(int left, int right) {        for (int out = left + 1; out <= right; out++) {            int temp = arr[out];            int in = out;            while (in > left && arr[in - 1] >= temp) {                arr[in] = arr[in - 1];                --in;            }            arr[in] = temp;        }    }    private int medianOf3(int left, int right) {/** 经过medianOf3排序,组最左项肯定小于或等于pivot，并且返回右二项为pivot */        int center=(left+right)/2;        if (arr[left]>arr[center]){            swap(left,center);        }        if (arr[left]>arr[right]){            swap(left,right);        }        if (arr[center]>arr[right]){            swap(center,right);        }        swap(center,right-1);        return arr[right-1];    }    //-----------quickSort end------------------------    @Test    public void bubble(){        System.out.print("冒泡法排序:");        bubbleSort();        display();    }    @Test    public void selection(){        System.out.print("选择法排序:");        selectionSort();        display();    }    @Test    public void insert(){        System.out.print("插入法排序:");        insertSort();        display();    }    @Test    public void recMerge(){        System.out.print("归并排序:");        int[] workSpace=new int[arr.length];//新开辟一个一样大小的数组，实际上用到的空间可能都不到一半        recMergeSort(workSpace,0,arr.length-1);        display();    }    @Test    public void shell(){        System.out.print("希尔排序:");        shellSort();        display();    }    @Test    public void quick(){        System.out.print("快速排序:");        quickSort(0, arr.length - 1);        display();    }}