import java.util.*; public class Solution { /** * 代码中的类名、方法名、参数名已经指定,请勿修改,直接返回方法规定的值即可 * * * @param numbers int整型一维数组 * @return int整型 */ public int duplicate (int[] numbers) { int[] help = new int[numbers.length]; for (int i=0;i<numbers.length;i++) { help[i] = -1; } for (int i=0;i<numbers.length;i++) { int cur = numbers[i]; if (help[cur]!=-1) { return cur; } else { help[cur] = cur; } } return -1; } }