常见排序算法

package Sort;

public class Main {

    private void printArr(int[] arr) {
        for (int i: arr) {
            System.out.print(i + " ");
        }
    }
    private void bubbleSort(int[] arr) {
        for (int i = 0; i < arr.length; i++) {
            for (int j = 0; j < arr.length - 1 - i; j++) {
                if (arr[j] > arr[j + 1]){
                    int temp = arr[j];
                    arr[j] = arr[j + 1];
                    arr[j + 1] = temp;
                }
            }
        }
    }

    private void insertSort(int[] arr) {
        for (int i = 1; i < arr.length; i++) {
            int temp = arr[i];
            int j;
            for (j = i - 1; j >= 0 && arr[j] > temp; j--) {
                arr[j + 1] = arr[j];
            }
            arr[j + 1] = temp;
        }
    }

    private void selectSort(int[] arr) {
        for (int i = 0; i < arr.length; i++){
            int minIndex = i;
            for (int j = i + 1; j < arr.length; j++) {
                if (arr[j] < arr[minIndex]) {
                    minIndex = j;
                }
            }
            if (minIndex != i) {
                int temp = arr[i];
                arr[i] = arr[minIndex];
                arr[minIndex] = temp;
            }
        }
    }
    private void swap(int[] arr, int i, int j) {
        int temp = arr[i];
        arr[i] = arr[j];
        arr[j] = temp;
    }

    private void quickSort(int[] arr, int start, int end) {
        if (start < end) {
            int l = start;
            int r = end;
            int temp = arr[start];
            while (l < r) {
                while (l < r && arr[r] >= temp) r--;
                arr[l] = arr[r];
                while (l < r && arr[l] <= temp) l++;
                arr[r] = arr[l];
            }
            arr[l] = temp;
            quickSort(arr, start, l - 1);
            quickSort(arr, l + 1, end);
        }
    }

    private static void shellSort(int[] arr) {
        for (int d = arr.length / 2; d >= 1; d /= 2) {
            for (int i = d; i < arr.length; i++) {
                int temp = arr[i];
                int j;
                for (j = i - d; j >= 0 && arr[j] > temp; j -= d) {
                    arr[j + d] = arr[j];
                }
                arr[j + d] = temp;
            }
        }
    }

    public static void merge(int[] arr, int left, int mid, int right){
        int[] temp = new int[arr.length];
        int p1 = left, k = left;
        int p2 = mid + 1;
        while (p1 < mid && p2 < right){
            if (arr[p1] <= arr[p2]){
                temp[k++] = arr[p1++];
            }
            else{
                temp[k++] = arr[p2++];
            }
        }
        while (p1 < mid) temp[k++] = arr[p1++];
        while (p2 < right) temp[k++] = arr[p2++];
        for (int i = left; i < right; i++){
            arr[i] = temp[i];
        }
    }
    public static void mergeSort(int[] arr, int start, int end){
        //要注意递归的结束条件
        if (start < end){
            int mid = (start + end) / 2;
            mergeSort(arr, start, mid);
            mergeSort(arr, mid + 1, end);
            merge(arr, start, mid, end);
        }
    }

    public static void main(String[] args) {
        Main test = new Main();
        int[] arr = new int[]{34, 23, 9, 12, 5, 78, 20, 4, 14, 56, 89, 3452};
//        test.bubbleSort(arr);
//        test.insertSort(arr);
//        test.selectSort(arr);
//        test.quickSort(arr, 0, arr.length - 1);
//        test.shellSort(arr);
        test.mergeSort(arr, 0, arr.length);
        test.printArr(arr);


    }
}