冒泡排序，归并排序

排序算法

冒泡排序

public class BubbleSort {
    public static void bubbleSort(int[] list){
        boolean flag = true;
        for (int i = 1; i < list.length && flag; i++) {
            flag=false;
            for (int j=0; j<list.length-i; j++){
                if (list[j]>list[j+1]){
                    int temp= list[j];
                    list[j]=list[j+1];
                    list[j+1]=temp;
                    flag=true;
                }
            }

        }
    }

    public static void main(String[] args) {
        int[] list={2,2,3,3,1,4,5,6,-1,19};
        bubbleSort(list);
        for (int i = 0; i < list.length; i++) {
            System.out.println(list[i]);
        }
    }
}

归并排序

拆分 然后 合并，分治思想

public class MergeSort {
    public static void mergeSort(int[] list){
        if (list.length>1){
            //Merge sort the first half
            int[] firstHalf = new int[list.length/2];
            System.arraycopy(list,0,firstHalf,0,list.length/2);
            mergeSort(firstHalf);

            //Merge sort the second half
            int secondHalfLength = list.length-list.length/2;
            int[] secondHalf = new int[secondHalfLength];
            System.arraycopy(list,list.length/2, secondHalf, 0, secondHalfLength);
            mergeSort(secondHalf);

            //Merge the first half with the second half
            int[] temp=merge(firstHalf,secondHalf);
            System.arraycopy(temp,0,list,0,list.length);

        }
    }
    private static int[] merge(int[] list1, int[] list2){
        int[] temp=new int[list1.length+list2.length];
        //current index in list1
        int current1=0;
        //current index in list2
        int current2=0;
        //current index in temp
        int current=0;
        while (current1<list1.length && current2< list2.length){
            if (list1[current1]<list2[current2]){
                temp[current++]=list1[current1++];
            }else {
                temp[current++]=list2[current2++];
            }
        }
        while (current1< list1.length){
            temp[current++]=list1[current1++];
        }
        while (current2< list2.length){
            temp[current++]=list2[current2++];
        }
        return temp;

    }

    public static void main(String[] args) {
        int[] list={2,3,4,1,-2,7,18};
        mergeSort(list);
        for (int i = 0; i < list.length; i++) {
            System.out.println(list[i]);
        }
    }
}