常見排序算法Java實現

想起來去年的現在正在學習數據結構，時間好快哦。今天在微博加到一個漂亮女孩在的微信，她說看我評論比較搞笑，是我太沙雕了嗎，不，不是的，我只是一個又皮又欠揍的可愛男孩子。

參考嚴蔚敏，吳偉民編著的《數據結構c語言版》，整理了幾個常用的排序算法，用Java實現了。

package sorttest;
import java.util.Arrays;
import java.util.Scanner;

public class SortTest {
    public static void main(String[] args) {
        int nums[] = getNums();

//        buddleSort(nums);//冒泡排序

//        selectionSort(nums);//選擇排序

//        insertionSort(nums);//插入排序

//        shellsort(nums);//希爾排序

//       nums =  mergeSort(nums);//歸併排序

        quickSort(nums);//快速排序

        for (int in : nums) {
            System.out.print(in + "  ");
        }

    }

    /**
     * 冒泡排序
     * @param nums
     * @return
     */
   static void buddleSort(int[] nums) {
        int length = nums.length;
        for (int i = length;i > 0; i--) {
            for (int j = 0; j < i-1; j++) {
                if (nums[j] > nums[j+1]) {
                    int tem = nums[j];
                    nums[j] = nums[j+1];
                    nums[j+1] = tem;
                }
            }
        }
    }

    /**
     *選擇排序
     * @param nums
     * @return
     */
    static void selectionSort(int[] nums) {
       int length = nums.length;
       for (int i = 0; i < length; i++) {
           int min = i;
           for (int j = i; j < length; j++){
               if (nums[j] < nums[min]) {
                   min = j;
               }
           }
           if (min != i) {
               int tem = nums[i];
               nums[i] = nums[min];
               nums[min] = tem;
           }
       }
    }

    /**
     *插入排序
     * @param nums
     * @return
     */
    static void insertionSort(int[] nums) {
        int length = nums.length;
        for (int i = 0; i < length-1; i++) {
            int num = nums[i+1];
            int j = i;
           while (num < nums[j]) {
               nums[j+1] = nums[j];
               j--;
           }
           nums[j+1] = num;
        }
    }

    /**
     *希爾排序
     * @param nums
     * @return
     */
    static void shellsort(int[] nums) {
        System.out.println();
        int length = nums.length;
        int gap = length/2;//增量
        while (gap > 0) {
            for (int i = gap; i < length; i++) {
                int num = nums[i];
                int j = i;
                while (num < nums[j-gap]) {
                    nums[j] = nums[j-gap];
                    j = j - gap;
                }
                nums[j] = num;
            }
            gap = gap/2;
        }
    }

    /**
     *歸併排序
     * @param nums
     */
    static int[] mergeSort(int[] nums) {
        int mid = nums.length/2;
        if (nums.length > 1) {
            int[] left = Arrays.copyOfRange(nums, 0, mid);
            int[] right = Arrays.copyOfRange(nums, mid, nums.length);
            return merge(mergeSort(left), mergeSort(right));
        } else return nums;

    }

    /**
     *歸併算法
     * @param left
     * @param right
     * @return
     */
    static int[] merge(int[] left,int[] right) {
        int[] res = new int[left.length + right.length];
        int j = 0, i = 0, index = 0;
        for (index = 0; index < res.length; index++) {
            if (i >= left.length) {
                res[index] = right[j++];
            }else if (j >= right.length) {
                res[index] = left[i++];
            } else if (left[i] < right[j]) {
                res[index] = left[i++];
            } else {
                res[index] = right[j++];
            }
        }
        return res;
    }

    /**
     * 快速排序
     * @param nums
     */
    static void quickSort(int[] nums) {
        int leftprivot = quikSortOne(nums, 0, nums.length-1);
        int rightprivot = leftprivot;
        while (leftprivot > 1) {
            leftprivot = quikSortOne(nums, 0, leftprivot-1);
        }
        while (rightprivot < nums.length-2) {
            rightprivot = quikSortOne(nums, rightprivot+1, nums.length-1);
        }

    }

    /**
     * 一趟快速排序
     * @param nums
     * @param i 要排的數組起始位置
     * @param j 要排的數組末尾位置
     */
    static int quikSortOne(int[] nums, int i, int j) {
        int low = i;
        int high = j;
        int privotkey = nums[i];
        int privot = i;
        while (low < high) {
            while (low < high && privotkey <= nums[high]) high--;
            int tem1 = nums[high];
            nums[high] = nums[low];
            nums[low] = tem1;
            privot = high;
            while (low < high && privotkey >= nums[low]) low++;
            int tem2 = nums[high];
            nums[high] = nums[low];
            nums[low] = tem2;
            privot = low;
        }
        return privot;
    }



    /**
     * 輸入函數
     * @return
     */
    static int[] getNums() {
        Scanner scanner = new Scanner(System.in);
        String s = scanner.nextLine();
        String[] ss = s.split(" ");
        int[] nums = new int[ss.length];
        int k = 0;
        for (String s1 : ss) {
            nums[k] = Integer.valueOf(s1);
            k++;
        }

        return nums;
    }
}