Anagram

Valid Anagram

• Using hash table or array of 256 to store string a
• Iterate through b to check if characters match

Group Anagrams

• We need to use a hash map unordered_map to store each group
• We will use a sorted version of each anagram as the key
• There are two ways to find the sorted anagram for each word
• The first one is to use sorting, then check if key exist
• The second one is to use array to count each character in word, then iterate through the array to get the sorted key.