与AcWing 13. 找出数组中重复的数字类似，用hash表

class Solution(object):
    def duplicateInArray(self, nums):
        """
        :type nums: List[int]
        :rtype int
        """
        n=len(nums)
        hash_table = [0 for x in range(0,n+1)]

        for i in nums:
            hash_table[i]+=1
            if hash_table[i]>1:
                return i
        return -1