https://oj.leetcode.com/problems/anagrams/
O(n m log m) time complexity, O(m n) space complexity, m is the average length of strings and n is count of strings.
anagrams.v1.Solution(760 ms time cost): Two pass solution.
anagrams.v2.Solution(768 ms time cost): Solve this problem with only one pass, and more space efficient.