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Companies
Amazon
String

String

Overall Progress0/153(0%)

Easy

0/33

Medium

0/79

Hard

0/41

Longest Substring Without Repeating Characters

Medium

Longest Palindromic Substring

Medium

Valid Parentheses

Easy

Generate Parentheses

Medium

Medium

Letter Combinations of a Phone Number

Medium

Longest Common Prefix

Easy

Minimum Window Substring

Hard

Medium

Medium

Medium

Roman to Integer

Easy

Longest Common Subsequence

Medium

Palindrome Partitioning

Medium

Medium

Longest Valid Parentheses

Hard

Easy

Find All Anagrams in a String

Medium

Regular Expression Matching

Hard

Hard

Medium

Permutation in String

Medium

Implement Trie (Prefix Tree)

Medium

Longest Repeating Character Replacement

Medium

Partition Labels

Medium

Serialize and Deserialize Binary Tree

Hard

Valid Palindrome

Easy

Longest Palindromic Subsequence

Medium

Remove K Digits

Medium

Easy

Hard

Evaluate Division

Medium

Isomorphic Strings

Easy

First Unique Character in a String

Easy

Medium

Easy

Remove Duplicate Letters

Medium

Reorganize String

Medium

Sort Characters By Frequency

Medium

Wildcard Matching

Hard

Top K Frequent Words

Medium

Design Add and Search Words Data Structure

Medium

Backspace String Compare

Easy

Integer to Roman

Medium

Hard

Multiply Strings

Medium

Minimum Remove to Make Valid Parentheses

Medium

Medium

Distinct Subsequences

Hard

Remove All Adjacent Duplicates In String

Easy

Basic Calculator

Hard

Valid Parenthesis String

Medium

Basic Calculator II

Medium

Hard

Reverse Words in a String III

Easy

Remove Invalid Parentheses

Hard

Remove All Adjacent Duplicates in String II

Medium

Medium

Palindrome Partitioning II

Hard

Greatest Common Divisor of Strings

Easy

String Compression

Medium

Minimum Insertion Steps to Make a String Palindrome

Hard

Easy

Easy

Find the Difference

Easy

Shortest Common Supersequence

Hard

Minimum Deletions to Make Character Frequencies Unique

Medium

String to Integer (atoi)

Medium

Verifying an Alien Dictionary

Easy

Medium

Search Suggestions System

Medium

Reverse Vowels of a String

Easy

Letter Case Permutation

Medium

Palindrome Pairs

Hard

Alien Dictionary

Hard

Flip String to Monotone Increasing

Medium

Find Common Characters

Easy

Easy

Medium

Concatenated Words

Hard

Text Justification

Hard

Robot Bounded In Circle

Medium

Integer to English Words

Hard

Maximum Number of Vowels in a Substring of Given Length

Medium

Serialize and Deserialize BST

Medium

Repeated DNA Sequences

Medium

Minimum Genetic Mutation

Medium

Reverse Substrings Between Each Pair of Parentheses

Medium

Medium

Compare Version Numbers

Medium

Longest Happy String

Medium

Smallest Subsequence of Distinct Characters

Medium

Repeated String Match

Medium

Decoded String at Index

Medium

Robot Return to Origin

Easy

Break a Palindrome

Medium

Prefix and Suffix Search

Hard

Longest Duplicate Substring

Hard

Find Words That Can Be Formed by Characters

Easy

Reorder Data in Log Files

Medium

Design Search Autocomplete System

Hard

Encode and Decode TinyURL

Medium

Substring with Concatenation of All Words

Hard

Number of Atoms

Hard

Uncommon Words from Two Sentences

Easy

Hard

Parsing A Boolean Expression

Hard

Most Common Word

Easy

Remove Palindromic Subsequences

Easy

Recover a Tree From Preorder Traversal

Hard

Decrypt String from Alphabet to Integer Mapping

Easy

Find Duplicate File in System

Medium

Design In-Memory File System

Hard

Easy

Minimum Window Subsequence

Hard

Find the Shortest Superstring

Hard

One Edit Distance

Medium

Numbers At Most N Given Digit Set

Hard

Iterator for Combination

Medium

Longest Absolute File Path

Medium

Find the Closest Palindrome

Hard

Minimum Length of String After Deleting Similar Ends

Medium

K-Similar Strings

Hard

Basic Calculator III

Hard

Split Array into Fibonacci Sequence

Medium

Shortest Word Distance II

Medium

Serialize and Deserialize N-ary Tree

Hard

Swap For Longest Repeated Character Substring

Medium

Camelcase Matching

Medium

Word Pattern II

Medium

Alphabet Board Path

Medium

String Matching in an Array

Easy

Sentence Similarity II

Medium

Maximum Number of Non-Overlapping Substrings

Hard

Easy

Rearrange Words in a Sentence

Medium

Next Closest Time

Medium

Complex Number Multiplication

Medium

Encode String with Shortest Length

Hard

Design File System

Medium

Find K-Length Substrings With No Repeated Characters

Medium

Solve the Equation

Medium

Minimum Possible Integer After at Most K Adjacent Swaps On Digits

Hard

Design Compressed String Iterator

Easy

Vowel Spellchecker

Medium

Count The Repetitions

Hard

Number of Days Between Two Dates

Easy

Index Pairs of a String

Easy

Remove Vowels from a String

Easy

Synonymous Sentences

Medium

Medium

Build Binary Expression Tree From Infix Expression

Hard

Sort Features by Popularity

Medium

Compiler Status