LeetCode---287. Find the Duplicate Number

题目

给出一个含有n+1个元素的数组，里面的元素值在1到n的范围内，找出重复的数字，假设只存在一个重复的数字，该数字的次数可能出现多次。

Python题解

class Solution:
    def findDuplicate(self, nums):
        """
        :type nums: List[int]
        :rtype: bool
        """
        if len(nums) <= 1:
            return -1
        slow, fast = nums[0], nums[nums[0]]
        while slow != fast:
            slow = nums[slow]
            fast = nums[nums[fast]]
        fast = 0
        while fast != slow:
            fast = nums[fast]
            slow = nums[slow]
        return slow