【Java之路】Java几个排序算法的简单实现

插入排序

package Algorithm;

public class InsertSort {
    private static int[] insertSort(int[] array) {
        for(int i=1; i<array.length; i++) {
            for(int j=i; j>0; j--) {
                if(array[j] < array[j-1]) {
                    int tmp = array[j];
                    array[j] = array[j-1];
                    array[j-1] = tmp;
                }
            }
        }
        return array;
    }
    public static void main(String[] args) {
        int[] array = {1, 1, 4, 5, 1, 4, 8, 1, 0};
        int[] result = insertSort(array);
        for (int value : result) {
            System.out.print(value + " ");
        }
    }
}

快速排序

package Algorithm;

public class QuickSort {
    public static void quickSort(int[] num, int left, int right) {
        if(left >= right) return;
        int key = num[left];
        int i = left, j = right;
        while(i < j) {
            while (num[j] >= key && i < j) {
                j--;
            }
            while (num[i] <= key && i < j) {
                i++;
            }
            if(i < j) {
                int tmp = num[i];
                num[i] = num[j];
                num[j] = tmp;
            }
        }
        num[left] = num[i];
        num[i] = key;
        quickSort(num, left, i-1);
        quickSort(num, i+1, right);
    }

    public static void main(String[] args) {
        int[] num = {1, 5, 6, 3, 4, 1, 4, 5};
        quickSort(num, 0, num.length-1);
        for(int i : num) {
            System.out.print(i + " ");
        }
    }
}