Four kinds of common sort

One, select the sort

Package testcode;

public class Run {public
    static void Main (string[] args) {  
    int[] arr = {5,4,8,9};
    Selectsort (arr);
    for (int i=0;i<arr.length;i++) {
        System.out.print (arr[i]+ "");
    }
    }

    private static void Selectsort (int[] arr) {
        //TODO auto-generated method stub
        int n = arr.length;
        int tmp =0;
        int flag = 0;
        for (int i=0;i<n;i++) {
            tmp = arr[i];
            Flag =i;
            for (int j=i+1;j<n;j++) {
                if (arr[j]<tmp) {
                    tmp = arr[j];
                    Flag = j;
                }
            }
            if (flag!=i) {
                Arr[flag] = arr[i];
                Arr[i] = tmp;}}}  

Results:

Second, insert sort

Package testcode;

public class Run {public
    static void Main (string[] args) {  
    int[] arr = {5,4,8,9};
    Insertsort (arr);
    for (int i=0;i<arr.length;i++) {
        System.out.print (arr[i]+ "");
    }
    }

    private static void Insertsort (int[] arr) {
        //TODO auto-generated method stub
        int temp=0;
        Int J =0;
        if (arr!=null) {for
            (int i=1;i<arr.length;i++) {
                temp =arr[i];
                j=i;
                if (arr[j-1]>temp) {while
                    (j>=1&&arr[j-1]>temp) {
                        arr[j] = arr[j-1];
                        j--
                    }
                }
                ARR[J] = temp;}}}  

Run Result:

Note: A For loop +while loop while (j>=1&&arr[j-1]>temp) termination condition

Two variables save Arr[i] and subscript information Three, merge sort MergeSort

Package testcode;
    public class Run {public static void main (string[] args) {int[] arr = {5,4,8,9};
    MergeSort (arr,0,arr.length-1);
    for (int i=0;i<arr.length;i++) {System.out.print (arr[i]+ "");
        } private static void MergeSort (int[] arr,int Start,int end) {//TODO auto-generated method stub
            if (start<end) {int mid = (start+end) >>1;
            MergeSort (Arr,start,mid);
            MergeSort (Arr,mid+1,end);
        Merge (Arr,start,mid,end); }} private static void merge (int[] arr, int left,int mid, int right) {//TODO auto-generated Method St
        UB int i = left;
        int j = mid+1;
        int k=0;
        int[] tmp = new Int[arr.length]; while (i<=mid&&j<=right) {//Termination condition with equal sign, closed interval if (Arr[i]<=arr[j]) {tmp[k++] = arr[i++]
            ;
            } else{tmp[k++] = arr[j++]; }} WHILe (i<=mid) {tmp[k++] = arr[i++];
        while (J<=right) {tmp[k++] = arr[j++]; for (int m = 0;m<k;m++) {Arr[left+m] = tmp[m];//starting position is left+m}}}

Run Result:

Three while (..) Cycle Four, fast row

Package testcode;

public class Run {public
    static void Main (string[] args) {  
    int[] arr = {5,4,8,9};
    QuickSort (arr,0,arr.length-1);
    for (int i=0;i<arr.length;i++) {
        System.out.print (arr[i]+ "");
    }
    }

    private static void QuickSort (int[] arr,int Start,int end) {
        //TODO auto-generated method stub
        int i=start;
  
   int J =end;
        int index = arr[i];
        if (i>=j) {return
            ;
        }
        while (I<J) {while
            (i<j && arr[j]>=index) {
                j--;
            }
            if (i<j) {
                arr[i++] = arr[j];
            }
            while (I<j && arr[i]<index) {
                i++;
            }
            if (i<j) {
                arr[j--] = Arr[i];
            }
        }
        Arr[i] = index;
        QuickSort (arr,start,i);
        QuickSort (arr,i+1,end);
    }


  

Run Result:

4 5 8 9