hash-table.md

Hash Table

Concept

• What is hash?
• How do you make hash?
• What is Hash Table?
• What do you have to care when you create the Hash Table?
• What is good(bad) about Hash Table compare to array?
  • when is better to use Hash Table over array

Analysis

What are the time complixity of

• add(insert)
• get value by key
• find value
• remove key, value
• update value

Exercise

Exercise 1

Let's try to implement your own hash function. There is a good leedcode question here!

• https://leetcode.com/problems/design-hashmap/

• Rules

  • Do not ever use pre existing hash table API
  • If you use an array, try to fixed the size with 1000

Exercise 2 (Optional)

Let's try to sovle some leetcode qusiton. These can be optimized by leveraging array and hash table data structure💪

• https://leetcode.com/problems/two-sum/
• https://leetcode.com/problems/first-unique-character-in-a-string/
• (optional) https://leetcode.com/problems/minimum-index-sum-of-two-lists/

References

https://leetcode.com/explore/learn/card/hash-table/

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Set

Q: Concept

• What is Set?
• What is Set vs Hash Table?
  • when is better to use Set over Hash Table