Topic
String problems
167 problems: 60 easy, 74 medium, 33 hard.
Easy (60)
- Palindrome Number
- Valid Parentheses
- Valid Anagram
- First Unique Character in a String
- Valid Palindrome
- Length of Last Word
- Add Binary
- Ransom Note
- Is Subsequence
- Implement Queue using Stacks
- Palindrome Linked List
- Excel Sheet Column Number
- Valid Palindrome II
- Find the Index of the First Occurrence
- Add Strings
- Reverse Words in a String III
- Largest Odd Number in String
- Minimum Changes To Make Alternating Binary String
- Reformat Phone Number
- Make The String Great
- Maximum Repeating Substring
- Reverse Words in String III
- Repeated Substring Pattern
- First Unique Character in String
- Backspace String Compare
- Remove All Adjacent Duplicates In String
- Remove Outermost Parentheses
- Thousand Separator
- Reformat Date
- Check if the Sentence Is Pangram
- Find the Difference
- Reverse Vowels of a String
- Student Attendance Record I
- To Lower Case
- Split a String in Balanced Strings
- Goal Parser Interpretation
- Count Binary Substrings
- Day of the Year
- Count Asterisks
- Largest 3-Same-Digit Number
- Percentage of Letter in String
- Minimum Recolors to Get K Consecutive Black Blocks
- Calculate Digit Sum of a String
- Capitalize the Title
- Decode the Message
- Count Vowel Substrings
- Base 7
- Merge Strings Alternately
- Word Pattern
- Isomorphic Strings
- Single-Row Keyboard
- License Key Formatting
- Longest Palindrome
- Goat Latin
- Increasing Decreasing String
- Count Good Substrings
- Count Vowels
- Count Consonants
- Reverse Word Order
- Capitalize Words
Medium (74)
- Longest Substring Without Repeating Characters
- Word Break
- Decode Ways
- Word Search
- Longest Palindromic Substring
- String to Integer (atoi)
- Integer to Roman
- Basic Calculator II
- LRU Cache
- Decode String
- Accounts Merge
- Reorganize String
- Palindrome Partitioning
- Fraction to Recurring Decimal
- Longest Repeating Character Replacement
- Permutation in String
- Time Based Key-Value Store
- Longest Palindromic Subsequence
- Interleaving String
- Longest Common Subsequence
- Partition Labels
- Valid Parenthesis String
- Longest Repeating Substring
- Count and Say
- Multiply Strings
- Reverse Words in a String
- Design Add and Search Words Data Structure
- Largest Number
- Longest String Chain
- Design Browser History
- Repeated String Match
- Find All Anagrams in a String
- Longest Substring with At Most K Distinct Characters
- Restore IP Addresses
- Delete Operation for Two Strings
- Minimum ASCII Delete Sum for Two Strings
- Simplify Path
- Zigzag Conversion
- Push Dominoes
- Decoded String at Index
- Construct Smallest Number From DI String
- Get Equal Substrings Within Budget
- Replace the Substring for Balanced String
- Sum of Beauty of All Substrings
- Number of Good Ways to Split a String
- Minimum Deletions to Make Character Frequencies Unique
- Palindromic Substrings
- Count Sorted Vowel Strings
- Verify Preorder Serialization of Binary Tree
- Smallest String With Swaps
- Minimum Add to Make Parentheses Valid
- Maximum Number of Vowels in a Substring
- Score of Parentheses
- Remove K Digits
- Minimum Penalty for a Shop
- Determine if Two Strings Are Close
- Optimal Partition of String
- Removing Stars From a String
- Simplify Unix Path
- Letter Case Permutation
- Sort Characters By Frequency
- Verify Preorder Serialization
- Complex Number Multiplication
- Remove All Adjacent Duplicates in String II
- Step-By-Step Directions From a Binary Tree Node to Another
- Maximize the Confusion of an Exam
- Generate Random Point in a Circle
- Check If a String Can Break Another String
- Minimum Suffix Flips
- Count Substrings That Differ by One Character
- Minimum Genetic Mutation
- Pattern Count (Non-overlapping)
- Z-Function Maximum
- Count Distinct Substrings
Hard (33)
- Longest Valid Parentheses
- Minimum Window Substring
- Regular Expression Matching
- Edit Distance
- Wildcard Matching
- Alien Dictionary
- Expression Add Operators
- Word Search II
- Distinct Subsequences
- Basic Calculator
- Palindrome Partitioning II
- Word Break II
- Rearrange String k Distance Apart
- Number of Atoms
- Stickers to Spell Word
- Strange Printer
- Scramble String
- Count Different Palindromic Subsequences
- Longest Duplicate Substring
- Shortest Palindrome
- Palindrome Pairs
- Decode Ways II
- Integer to English Words
- Valid Number
- Minimum Window Subsequence
- Student Attendance Record II
- Similar String Groups
- Find Longest Awesome Substring
- Orderly Queue
- Freedom Trail
- Smallest Good Base
- Count Vowels Permutation
- Distinct Echo Substrings