merge排序

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merge排序关键在于merge函数
import leet.ArrayUtils;import java.util.Arrays;/** * Created by fhqplzj on 16-9-29 at 下午6:58. */public class AnotherMergeSort {    private int[] aux;    public void merge(int[] nums, int lo, int mid, int hi) {        System.arraycopy(nums, lo, aux, lo, hi - lo + 1);        int i = lo, j = mid + 1;        for (int k = lo; k <= hi; k++) {            if (i > mid) {                nums[k] = aux[j++];            } else if (j > hi) {                nums[k] = aux[i++];            } else if (aux[i] < aux[j]) {                nums[k] = aux[i++];            } else {                nums[k] = aux[j++];            }        }    }    private void sort(int[] nums, int lo, int hi) {        if (lo < hi) {            int mid = (lo + hi) >>> 1;            sort(nums, lo, mid);            sort(nums, mid + 1, hi);            merge(nums, lo, mid, hi);        }    }    public void sort(int[] nums) {        int n = nums.length;        aux = new int[n];        sort(nums, 0, n - 1);    }    public void sortBottomUp(int[] nums) {        int n = nums.length;        aux = new int[n];        for (int size = 1; size < n; size *= 2) {            for (int lo = 0; lo + size < n; lo += 2 * size) {                merge(nums, lo, lo + size - 1, Math.min(lo + 2 * size - 1, n - 1));            }        }    }    public static void main(String[] args) {        AnotherMergeSort anotherMergeSort = new AnotherMergeSort();        int[] nums = ArrayUtils.generateRandomIntArray(0, 100, 50);        System.out.println(Arrays.toString(nums));        anotherMergeSort.sortBottomUp(nums);        System.out.println(Arrays.toString(nums));    }}
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