Valid Anagram: count what matters
Use a frequency map to compare two strings, and understand when counting is a better fit than sorting. LeetCode 242, explained.
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Good engineering starts with understanding.
Practical explanations, working examples, and the trade-offs that matter. Learn a concept, then put it to work.
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Data structures & algorithms
Coming into focusSystem design
Coming into focusPractical engineering
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Learning path · 2 lessons
A first look at hashing
Two short lessons on using sets and frequency maps to solve array and string problems.
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Contains Duplicate: hash sets vs sorting
Learn when a set is the right tool, and what you trade away when you sort instead. A worked explanation of LeetCode 217.