[Python-leetcode287- ordering cycle] to find the number of repeats

Problem Description:

Given an n + 1 contains an integer array nums, which are digital (including 1 and n), found that the presence of at least one repeating integer between 1 to n. Assuming that only a unique integer, find the number of repeats.

Example 1:

Input: [1,3,4,2,2]
Output: 2
Example 2:

Input: [3,1,3,4,2]
Output: 3
Description:

You can not change the original array (assuming that the array is read-only).
Only use extra space O (1) is.
It is less than the time complexity of O (n2).
Only a duplicate array of numbers, but it may be repeated more than once.

 

Code:

class Solution:
    def findDuplicate(self, nums: List[int]) -> int:
        l,r=0,len(nums)-1
        while l<=r:
            if nums[l] != nums[nums[l]-1]:
                nums[nums[l]-1],nums[l]=nums[l],nums[nums[l]-1]
            else:
                l+=1
        for i in range(len(nums)):
            if i+1 != nums[i]:
                return nums[i]

result: