"Section 8: Strings — Easy/Medium"

📚 Vanakkam DSA Course (24 sections) · Hope AI — ML & DS Course

Overview

String manipulation is one of the most common interview topics. This section covers palindromes, anagrams, prefix matching, and character mapping.

---

Lessons

#	Lesson Name	Duration	Notes
1	Reverse String II	49m 10s
2	Valid Palindrome Approach 1	24m 12s
3	Valid Palindrome Approach 2	24m 17s
4	Largest Odd Number in a String	14m 59s
5	Longest Common Prefix	24m 36s
6	Valid Anagram	40m 57s
7	Isomorphic Strings	39m 55s
8	Group Anagrams Approach 1	21m 54s
9	Group Anagrams Approach 2	29m 30s

---

Lesson Checklist

• [ ] Reverse String II (49m 10s)
• [ ] Valid Palindrome Approach 1 (24m 12s)
• [ ] Valid Palindrome Approach 2 (24m 17s)
• [ ] Largest Odd Number in a String (14m 59s)
• [ ] Longest Common Prefix (24m 36s)
• [ ] Valid Anagram (40m 57s)
• [ ] Isomorphic Strings (39m 55s)
• [ ] Group Anagrams Approach 1 (21m 54s)
• [ ] Group Anagrams Approach 2 (29m 30s)

---

My Notes

Add your personal notes, key takeaways, and insights here as you progress through the section.

Key Patterns

• Two pointer — palindrome checks
• Hash map / frequency count — anagram, isomorphic
• Sorting — group anagrams approach 1
• Character array key — group anagrams approach 2

Problem Notes

Valid Palindrome

• Approach 1 (clean string first):
• Approach 2 (two pointers, skip non-alphanumeric):

Valid Anagram

• Use frequency count / sorted string

Isomorphic Strings

• Map chars from s → t and t → s bidirectionally

Group Anagrams

• Approach 1 (sort each word as key):
• Approach 2 (char frequency tuple as key):