题解 | #数组中重复的数字#

#
# 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
#
class Solution:
    def duplicate(self , numbers: List[int]) -> int:
        # write code here
        if len(numbers) == 0:
            return -1
        ans = set()
        #fin = 0
        for i in numbers:
            if i >= 0 and i <= len(numbers) - 1:
                if i not in ans:
                    ans.add(i)
                else:
                    return i
            else:
                return -1