find_the_duplicate_number.py

# Given an array of integers nums containing n + 1 integers where each integer is in the range [1, n] inclusive.

# There is only one repeated number in nums, return this repeated number.

# You must solve the problem without modifying the array nums and uses only constant extra space.

 

# Example 1:

# Input: nums = [1,3,4,2,2]
# Output: 2
# Example 2:

# Input: nums = [3,1,3,4,2]
# Output: 3

class Solution:
    def findDuplicate(self, nums: List[int]) -> int:
        Range = {}
        for i in range(1, len(nums)):
            Range[i] = 1
        
        for i in range(len(nums)):
            if Range[nums[i]] == 0:
                return nums[i]
            else:
                Range[nums[i]] -= 1