基本排序

import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import scala.actors.threadpool.Arrays;

import static org.junit.Assert.assertTrue;


public class Sort {

    int[] nums = new int[10000];

    public int[] bubbleSort(int[] nums) {
        for (int i = 0; i < nums.length; i++) {
            for (int j = i + 1; j < nums.length; j++) {
                if (nums[i] > nums[j]) {
                    int tmp = nums[i];
                    nums[i] = nums[j];
                    nums[j] = tmp;
                }
            }
        }
        return nums;
    }

    public int[] insertSort(int[] nums) {
        for (int i = 1; i < nums.length; i++) {
            int tmp = nums[i];
            int insertPos = i;
            for (int j = i - 1; j >= 0; j--) {
                if (nums[j] > tmp) {
                    nums[j + 1] = nums[j];
                    insertPos = j;
                }
            }
            nums[insertPos] = tmp;
        }
        return nums;
    }

    public int[] quickSort(int[] nums, int left, int right) {
        if (left < right) {
            int p = getPartition(nums, left, right);
            quickSort(nums, left, p - 1);
            quickSort(nums, p + 1, right);
        }
        return nums;
    }

    private int getPartition(int[] nums, int low, int hi) {
        int pivot = nums[low];
        while (low < hi) {
            while (hi > low && nums[hi] >= pivot) {
                --hi;
            }
            nums[low] = nums[hi];
            while (low < hi && nums[low] < pivot) {
                ++low;
            }
            nums[hi] = nums[low];
        }
        nums[low] = pivot;
        return low;
    }

    public int[] mergeSort(int[] nums, int low, int hi) {
        if (low < hi) {
            int mid = (low + hi) / 2;
            mergeSort(nums, low, mid);
            mergeSort(nums, mid + 1, hi);
            merge(nums, low, mid, hi);
        }
        return nums;
    }

    private void merge(int[] nums, int low, int mid, int hi) {
        int[] tmpNums = new int[hi - low + 1];
        int pos = 0;
        for (int i = low, j = mid + 1; i <= mid || j <= hi; ) {
            if (i > mid) {
                tmpNums[pos++] = nums[j++];
            } else if (j > hi) {
                tmpNums[pos++] = nums[i++];
            } else if (nums[i] < nums[j]) {
                tmpNums[pos++] = nums[i++];
            } else {
                tmpNums[pos++] = nums[j++];
            }
        }
        for (int i = 0; i < hi - low + 1; i++) {
            nums[low + i] = tmpNums[i];
        }
        tmpNums = null;
    }

    @Before
    public void init() {
        for (int i = 0; i < nums.length; i++) {
            nums[i] = (int) (Math.random() * 10000);
        }
    }

    @After
    public void check() {
        System.out.println(Arrays.toString(nums));
        int pre = Integer.MIN_VALUE;
        for (int num : nums) {
            assertTrue(pre <= num);
            pre = num;
        }

    }

    @Test
    public void test() {
        //nums = bubbleSort(nums);
        //nums = quickSort(nums, 0, nums.length - 1);
        mergeSort(nums, 0, nums.length - 1);
    }
}

　　

转载于:https://www.cnblogs.com/wqkant/p/9813704.html