1.时间复杂度

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2.快排

public class QuickSortTest {

    public static void main(String[] args) {
        int[] a = {2, 34, 56, 7, 9, 12, 33};
        quickSort(a, 0, a.length - 1);
        for (int i = 0; i < a.length; i++) {
            System.out.println(a[i]);
        }
    }

    public static void quickSort(int[] a, int left, int right) {
        int i = left;
        int j = right;
        if (i >= j) return;
        int temp = a[left];

        while (i < j) {
            while (i < j && temp >= a[i]) {
                i++;
            }
            while (i < j && temp <= a[j]) {
                j--;
            }
            if (i < j) {
                int m = a[i];
                a[i] = a[j];
                a[j] = m;
            }
        }
        a[left] = a[i];
        a[i] = temp;

        quickSort(a, left, i - 1);
        quickSort(a, i + 1, right);
    }
}