Relative Sort Array

public class Solution {
    public int[] RelativeSortArray(int[] arr1, int[] arr2) {
        var dict = new Dictionary<int, int>();
        var result = new int[arr1.Length];
        foreach(int elem in arr1)
        {
            if(dict.ContainsKey(elem))
                dict[elem]++;
            else 
               dict.Add(elem,1);
        }

        int i =0;
        foreach(int elem in arr2)
        {
            while(dict[elem] >0)
            {
             result[i] = elem;
             i++;
             dict[elem]--;
            }
            dict.Remove(elem);
        }
        var pq = new PriorityQueue<int,int>();
        foreach(var kv in dict)
        {   while(dict[kv.Key] >0)
            {
             pq.Enqueue(kv.Key, kv.Key);
             dict[kv.Key]--;
            }            
        }
        while(i < arr1.Length)
        {
            result[i] = pq.Dequeue();
            i++;
        }

        return result;
    }
}