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);
		}
	}

}