Most Frequent Number Following Key In an Array — LeetCode 2190 Python Solution

The problem

You are given a 0-indexed integer array nums. You are also given an integer key, which is present in nums.

Example

Input

nums = [1,100,200,1,100], key = 1

Output

100

Explanation

For target = 100, there are 2 occurrences at indices 1 and 4 which follow an occurrence of key.

Python solution

class Solution:
    def mostFrequent(self, nums: List[int], key: int) -> int:
        cnt = Counter()
        ans = mx = 0
        for a, b in pairwise(nums):
            if a == key:
                cnt[b] += 1
                if mx < cnt[b]:
                    mx = cnt[b]
                    ans = b
        return ans

Complexity

Pattern: Hash Map

Trade memory for time: remember what you have seen so the second pass never happens. LeetCode 2190. Most Frequent Number Following Key In an 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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