HTMLify

class Solution:
    def missingRange(self, arr, low, high):
        present_elements = set()
        for num in arr:
            if low <= num <= high:
                present_elements.add(num)
        
        result = []
        for i in range(low, high + 1):
            if i not in present_elements:
                result.append(i)
                
        return result