How hard is LeetCode 1497. Check If Array Pairs Are Divisible by k?

LeetCode 1497. Check If Array Pairs Are Divisible by k is rated Medium on LeetCode.

What is the time complexity of LeetCode 1497. Check If Array Pairs Are Divisible by k?

The Python solution on this page runs in O(n), where n is the length of the array \textit{arr}.

What is the space complexity of LeetCode 1497. Check If Array Pairs Are Divisible by k?

The Python solution on this page uses O(k) auxiliary space.

What topics does LeetCode 1497. Check If Array Pairs Are Divisible by k cover?

LeetCode 1497. Check If Array Pairs Are Divisible by k is tagged Array, Hash Table and Counting on LeetCode.

Check If Array Pairs Are Divisible by k — LeetCode 1497 Python Solution

MediumArrayHash TableCounting

Problem: #1497
Pattern: Hash Map
Reading time: 2 min
Source: leetcode.com

The problem

Given an array of integers arr of even length n and an integer k. We want to divide the array into exactly n / 2 pairs such that the sum of each pair is divisible by k.

Example

Input: arr = [1,2,3,4,5,10,6,7,8,9], k = 5
Output: true
Explanation: Pairs are (1,9),(2,8),(3,7),(4,6) and (5,10).

Python solution

Python

class Solution:
    def canArrange(self, arr: List[int], k: int) -> bool:
        cnt = Counter(x % k for x in arr)
        return cnt[0] % 2 == 0 and all(cnt[i] == cnt[k - i] for i in range(1, k))

Complexity

Measure	Complexity
Time	O(n), where n is the length of the array \textit{arr}
Space	O(k) auxiliary

Pattern: Hash Map

Trade memory for time: remember what you have seen so the second pass never happens. LeetCode 1497. Check If Array Pairs Are Divisible by k 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.

Frequently asked questions

How hard is LeetCode 1497. Check If Array Pairs Are Divisible by k?: LeetCode 1497. Check If Array Pairs Are Divisible by k is rated Medium on LeetCode.
What is the time complexity of LeetCode 1497. Check If Array Pairs Are Divisible by k?: The Python solution on this page runs in O(n), where n is the length of the array \textit{arr}.
What is the space complexity of LeetCode 1497. Check If Array Pairs Are Divisible by k?: The Python solution on this page uses O(k) auxiliary space.
What topics does LeetCode 1497. Check If Array Pairs Are Divisible by k cover?: LeetCode 1497. Check If Array Pairs Are Divisible by k is tagged Array, Hash Table and Counting on LeetCode.