EasyNo. 2341
Maximum Number of Pairs in Array — LeetCode 2341 Python Solution
- Pattern
- Hash Map
- Topics
- Array, Hash Table, Counting
- Reading time
- 2 min
- Source
- leetcode.com
The problem
You are given a 0-indexed integer array nums. In one operation, you may do the following: Choose two integers in nums that are equal.
Example
- Input
- nums = [1,3,2,1,3,2,2]
- Output
- [3,1]
- Explanation
- Form a pair with nums[0] and nums[3] and remove them from nums. Now, nums = [3,2,3,2,2].
Python solution
class Solution:
def numberOfPairs(self, nums: List[int]) -> List[int]:
cnt = Counter(nums)
s = sum(v // 2 for v in cnt.values())
return [s, len(nums) - s * 2]Complexity
- Time
- O(n)
- Space · auxiliary
- O(C)
Pattern: Hash Map
Trade memory for time: remember what you have seen so the second pass never happens. LeetCode 2341. Maximum Number of Pairs in Array is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Hash Table and Counting.
The hash map guide has the Python template for the pattern and the 709 LeetCode problems that use it.
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Frequently asked questions
- How hard is LeetCode 2341. Maximum Number of Pairs in Array?
LeetCode 2341. Maximum Number of Pairs in Array is rated Easy on LeetCode.
- What is the time complexity of LeetCode 2341. Maximum Number of Pairs in Array?
The Python solution on this page runs in O(n).
- What is the space complexity of LeetCode 2341. Maximum Number of Pairs in Array?
The Python solution on this page uses O(C) auxiliary space.
- What topics does LeetCode 2341. Maximum Number of Pairs in Array cover?
LeetCode 2341. Maximum Number of Pairs in Array is tagged Array, Hash Table and Counting on LeetCode.