String

String problems revolve around scanning, comparing, and transforming character sequences — often combined with hashing, two pointers, or a stack. Watch for in-place edits, character counts, and the difference between bytes and Unicode.

9 LeetCode problems solved with the String pattern. Practice them with spaced repetition so the pattern sticks.

• Find the Index of the First Occurrence in a StringEASY · O(n * m)
• Length of Last WordEASY · O(n)
• Longest Common PrefixEASY · O(S)
• Repeated Substring PatternEASY · O(n)
• Reverse String IIEASY · O(n)
• String to Integer (atoi)MEDIUM · O(n)
• Text JustificationHARD · O(n)
• Verifying an Alien DictionaryEASY · O(n * m)
• Zigzag ConversionMEDIUM · O(n)