First element to occur k times

prooblem statement

First element to occur k times

EasyAccuracy: 37.11%Submissions: 176K+Points: 2

Given an array of n integers. Find the first element that occurs atleast k number of times. If no such element exists in the array, then expect the answer to be -1.

Example 1:

Input :
n = 7, k = 2
a[] = {1, 7, 4, 3, 4, 8, 7}
Output :
4
Explanation :
Both 7 and 4 occur 2 times. But 4 is first that occurs twice.
As at index = 4, 4 has occurred twice whereas 7 appeared twice
at index 6.

Example 2:

Input :
n = 10, k = 3
a[] = {3, 1, 3, 4, 5, 1, 3, 3, 5, 4}
Output :
3
Explanation :
Here, 3 is the only number that appeared atleast 3 times in the array.

Your Task:
You don’t need to read input or print anything. Your task is to complete the function firstElementKTime() which takes the array a[], its size n, and an integer k as input arguments and returns the required answer. If the answer is not present in the array, return -1.

Expected Time Complexity: O(n).
Expected Auxiliary Space: O(n).

Constraints:
1 <= n <= 104
1 <= k <= 100
0 <= a[i] <= 200

Approach :

Construct a frequency hash map is we see the count ==k the return key immediately

solution

class Solution
{
    
    // Time : O(n) space : O(n)
    public int firstElementKTime(int n, int k, int[] a) { 
        Map<Integer,Integer> freHashMap=new HashMap<>();
        for(int i=0;i<n;i++){
            int count=freHashMap.containsKey(a[i]) ?
                      freHashMap.get(a[i]) : 0;
            
            freHashMap.put(a[i],++count);
            if(count==k) return a[i];
        }
        return -1;
    } 
}