201612-1 中间数 Java

思路：
先排序，两个count变量记录。有点暴力

import java.util.Arrays;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int a[] = new int[n];
        for(int i=0;i<n;i++) {
            a[i] = sc.nextInt();
        }
        Arrays.sort(a);
        int mid = (n-1)/2;
        int count1 = 0;
        int count2 = 0;
        for(int j=0;j<mid;j++) {
            if(a[j] < a[mid]) {
                count1++;
            }
        }
        for(int k=mid+1;k<n;k++) {
            if(a[k] > a[mid]) {
                count2++;
            }
        }
        if(count1 == count2) {
            System.out.println(a[mid]);
        }else {
            System.out.println(-1);
        }
    }

}