2404. Most Frequent Even Element

Problem

Given an integer array nums, return the most frequent even element.

If there is a tie, return the smallest one. If there is no such element, return -1.

  Example 1:

Input: nums = [0,1,2,2,4,4,1]
Output: 2
Explanation:
The even elements are 0, 2, and 4. Of these, 2 and 4 appear the most.
We return the smallest one, which is 2.

Example 2:

Input: nums = [4,4,4,9,2,4]
Output: 4
Explanation: 4 is the even element appears the most.

Example 3:

Input: nums = [29,47,21,41,13,37,25,7]
Output: -1
Explanation: There is no even element.

  Constraints:

• 1 <= nums.length <= 2000

• 0 <= nums[i] <= 10^5

Solution (Java)

class Solution {
    public int mostFrequentEven(int[] A) {
        HashMap<Integer,Integer> mp= new HashMap<>();
        int val=1000000,freq=0;
        for(var i:A){
            //if even element
            if(i%2==0){
                //increase frequency in map
                int curr= mp.getOrDefault(i,0)+1;
                mp.put(i,curr);
                //Update smallest with greatest frequency
                if(curr>freq || curr==freq && i<val){
                    val=i;
                    freq=curr;
                }
            }
        }
        return freq==0? -1 : val;
    }
}

Explain:

nope.

Complexity:

• Time complexity : O(n).
• Space complexity : O(n).