排序算法---归并排序

算法设计:

归并排序算法将数组分为两半，对每部分递归的应用归并排序。在两部分都排好序后，对他们进行归并。算法时间复杂度为O(nlogn)

public static void mergeSort(int[] list){    if(list.length>1){        mergeSort(list[0....list.length/2]);        mergeSort(list[list.length/2....list.length]);        merge list[0....list.length/2] with list[list.length/2....list.length]    }}

算法实现:

public class MergeSort {    public static void main(String[] args) {        int[] list={2,3,2,5,6,1,-2,3,14,12};        mergeSort(list);        System.out.print("{2,3,2,5,6,1,-2,3,14,12}" + " by insertionSort is {");        for (int i = 0; i < list.length; i++) {            System.out.print(list[i] + ",");        }        System.out.println("}");    }    public static void mergeSort(int[] list) {        if (list.length > 1) {            int[] firstHalf = new int[list.length / 2];            System.arraycopy(list, 0, firstHalf, 0, list.length / 2);            mergeSort(firstHalf);            int secondHalfLength = list.length - list.length / 2;            int[] secondHalf = new int[secondHalfLength];            System.arraycopy(list, list.length / 2, secondHalf, 0, secondHalfLength);            mergeSort(secondHalf);            merge(firstHalf, secondHalf, list);        }    }    public static void merge(int[] list1, int[] list2, int[] tmp) {        int current1 = 0;        int current2 = 0;        int current3 = 0;        while (current1 < list1.length && current2 < list2.length) {            if (list1[current1] < list2[current2])                tmp[current3++] = list1[current1++];            else                tmp[current3++] = list2[current2++];        }        while (current1 < list1.length)            tmp[current3++] = list1[current1++];        while (current2 < list2.length)            tmp[current3++] = list2[current2++];    }}