初级排序Java版代码记录

package test.sort;

import static io.snowfly.algorithms.sort.SortTest.exchange;
import static io.snowfly.algorithms.sort.SortTest.printArray;

public class SortTest {

    public static void main(String[] args) {
        System.out.println("hello algorithms in java sort");
        int[] arr = {3, 2, 1, 5, 4, 6, 8, 9, 7, 10, 13, 12, 11};
        printArray(arr);
        //insertSort(arr);
        //selectSort(arr);
        //bubbleSort(arr);
        // mergeSortRecursive(arr, new int[arr.length], 0, arr.length - 1);
        quickSortRecursive(arr, 0, arr.length - 1);
        printArray(arr);

    }

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

    static void selectSort(int[] arr) {
        for (int i = 0; i < arr.length; i++) {
            int index = i;
            for (int j = i + 1; j < arr.length; j++) {
                if (arr[j] < arr[index]) index = j;
            }
            if (index != i)
                exchange(arr, index, i);
        }
    }

    static void bubbleSort(int[] arr) {
        for (int i = 0; i < arr.length; i++) {
            for (int j = 0; j < arr.length - i - 1; j++) {
                if (arr[j] > arr[j + 1]) exchange(arr, j, j + 1);
            }
        }
    }

    static void mergeSortRecursive(int[] arr, int[] rest, int low, int high) {
        if (low >= high) return;
        int mid = low + (high - low) / 2;
        mergeSortRecursive(arr, rest, low, mid);
        mergeSortRecursive(arr, rest, mid + 1, high);
        int start1 = low;
        int end1 = mid;
        int start2 = mid + 1;
        int end2 = high;
        int k = low;
        while (start1 <= end1 && start2 <= end2) rest[k++] = arr[start1] < arr[start2] ? arr[start1++] : arr[start2++];
        while (start1 <= end1) rest[k++] = arr[start1++];
        while (start2 <= end2) rest[k++] = arr[start2++];
        for (k = low; k <= high; k++) {
            arr[k] = rest[k];
        }
    }

    static void quickSortRecursive(int[] arr, int low, int high) {
        if (low >= high) return;
        int pivot = low;
        int i = low;
        int j = high + 1;
        while (true) {
            while (arr[++i] < arr[pivot] && i < high) ;
            while (arr[--j] > arr[pivot] && j > low) ;
            if (i >= j) break;
            exchange(arr, i, j);
        }
        exchange(arr, pivot, j);
        quickSortRecursive(arr, low, pivot);
        quickSortRecursive(arr, pivot + 1, high);
    }

}