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2206. Divide Array Into Equal Pairs

Difficulty Topics

Description

You are given an integer array nums consisting of 2 * n integers.

You need to divide nums into n pairs such that:

  • Each element belongs to exactly one pair.
  • The elements present in a pair are equal.

Return true if nums can be divided into n pairs, otherwise return false.

 

Example 1:

Input: nums = [3,2,3,2,2,2]
Output: true
Explanation: 
There are 6 elements in nums, so they should be divided into 6 / 2 = 3 pairs.
If nums is divided into the pairs (2, 2), (3, 3), and (2, 2), it will satisfy all the conditions.

Example 2:

Input: nums = [1,2,3,4]
Output: false
Explanation: 
There is no way to divide nums into 4 / 2 = 2 pairs such that the pairs satisfy every condition.

 

Constraints:

  • nums.length == 2 * n
  • 1 <= n <= 500
  • 1 <= nums[i] <= 500

Solution

divide-array-into-equal-pairs.py
class Solution:
    def divideArray(self, nums: List[int]) -> bool:
        N = len(nums)
        n = N // 2

        counter = Counter(nums)

        for k, v in counter.items():
            if v == 1: return False

            n -= v // 2

        return n == 0