About This Pattern
Master the Hash Map / Frequency Counter pattern by practicing these problems organized by difficulty.Focus on the Key Signals - these are the indicators that tell you when to use this pattern.
Easy (3)
Valid Anagram
Given two strings s and t, return true if t is an anagram of s.
Key Signals:
Character frequencyCounting occurrencesComparison of collections
Valid Anagram
Given two strings s and t, return true if t is an anagram of s.
Key Signals:
Character frequencyCounting occurrencesComparison
Palindrome Permutation
Given a string, determine if a permutation of the string could form a palindrome.
Key Signals:
Character frequencyAt most one oddPalindrome properties