Count Complete Subarrays in an Array — Python

# Time:  O(n)
# Space: O(n)

import collections


# freq table, two pointers, sliding window
class Solution(object):
    def countCompleteSubarrays(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        nums_set = set(nums)
        result = left = 0
        cnt = collections.Counter()
        for right in xrange(len(nums)):
            cnt[nums[right]] += 1
            while len(cnt) == len(nums_set):
                cnt[nums[left]] -= 1
                if cnt[nums[left]] == 0:
                    del cnt[nums[left]]
                left += 1
            result += left
        return result