快速排序+二分查找练习

import java.util.Scanner;

public class QuickSort_BinarySearch {

    public void Scanner() {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int[] num = new int[n];
        for (int i = 0; i < n; i++){
            num[i] = scanner.nextInt();
        }
        out(num);
        quickSort(num, 0 , n-1);
        out(num);
        int target = scanner.nextInt();
        System.out.println(binarySearch(num, target));
    }

	// 快排
    public void quickSort(int[] num, int left, int right) {
        if (left > right) {
            return;
        }
        int i = left;
        int j = right;
        int flag = num[left];
        while (i != j) {
            while (num[j] > flag && i < j) {
                j--;
            }
            while (num[i] <= flag && i < j) {
                i++;
            }
            int temp;
            if (i < j) {
                temp = num[j];
                num[j] = num[i];
                num[i] = temp;
            }
        }

        num[left] = num[i];
        num[i] = flag;

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

	// 二分查找
    public int binarySearch(int[] num, int target) {
        int left = 0;
        int right = num.length - 1;
        while (left <= right) {
            int mid = (left + right) / 2;
            if (num[mid] == target) {
                return mid;
            } else if (num[mid] < target) {
                left = mid + 1;
            } else if (num[mid] > target) {
                right = mid - 1;
            }
        }
        return -1;
    }

    public void out(int[] num) {
        System.out.println();
        for (int i = 0; i < num.length; i++) {
            System.out.print(num[i] + "\t");
        }
    }

    public static void main(String[] args) {
        new QuickSort_BinarySearch().Scanner();
    }
}