• Alien Dictionary

  Time: O(n) Space: O(1)

• Basic Calculator

  Time: O(n) Space: O(n)

• Basic Calculator II

  Time: O(n) Space: O(n)

• Best Time to Buy and Sell Stock II

  Time: O(n) Space: O(1)

• Best Time to Buy and Sell Stock III

  Time: O(n) Space: O(1)

• Binary Search Tree Iterator

  Time: O(n) Space: O(n)

• Binary Tree Maximum Path Sum

  Time: O(h) Space: O(1)

• Binary Tree Zigzag Level Order Traversal

  Time: O(n) Space: O(n)

• Burning Tree

  Time: O(n) Space: O(2^h)

• Cheapest Flights Within K Stops

  Time: O(n^k) Space: O(n²k)

• Cherry Pickup II

  Time: O(mn²) Space: O(mn²)

• Clone Graph

  Time: O(n) Space: O(n)

• Coin Change

  Time: O(n*amount) Space: O(amount)

• Combination Sum

  Time: O(2ⁿ) Space: O(n)

• Construct Binary Tree from Preorder and Inorder Traversal

  Time: O(h) Space: O(1)

• Convert Binary Tree to DLL

  Time: O(n) Space: O(h)

• Count and Say

  Time: O(n) Space: O(1)

• Count of Smaller Numbers After Self

  Time: O(nlogn) Space: O(n)

• Course Schedule II

  Time: O(V+E) Space: O(V+E)

• Course Schedule III

  Time: O(nlogn) Space: O(n)

• Decode String

  Time: O(n) Space: O(n)

• Decode Ways

  Time: O(n) Space: O(n)

• Detect Cycle Directed Graph

  Time: O(V+E) Space: O(V)

• Detect Cycle Undirected Graph

  Time: O(V+E) Space: O(V)

• Edit Distance

  Time: O(nm) Space: O(nm)

• Find K Closest Elements

  Time: O(n) Space: O(1)

• Find Median from Data Stream

  Time: O(1) Space: O(1)

• Find Minimum in Rotated Sorted Array

  Time: O(logn) Space: O(1)

• Find Peak Element

  Time: O(log n) Space: O(1)

• Find the Celebrity

  Time: O(n) Space: O(1)

• Find the Duplicate Number

  Time: O(n) Space: O(1)

• First Missing Positive

  Time: O(n) Space: O(1)

• Flatten Binary Tree to Linked List

  Time: O(n) Space: O(n)

• Gas Station

  Time: O(n) Space: O(1)

• Generate Parentheses

  Time: O(4ⁿ/n√n) Space: O(4ⁿ/n√n)

• Group Anagrams

  Time: O(nm) Space: O(nm)

• Group Shifted Strings

  Time: O(n) Space: O(n)

• House Robber II

  Time: O(n) Space: O(1)

• House Robber III

  Time: O(n) Space: O(1)

• Insert Delete GetRandom O1

  Time: O(1) Space: O(n)

• Integer to English Words

  Time: O(1) Space: O(1)

• K Closest Points to Origin

  Time: O(nlogk) Space: O(k)

• Koko Eating Bananas

  Time: O(logn) Space: O(1)

• Kth Smallest Element in a BST

  Time: O(h+k) Space: O(h)

• Kth Smallest Element in a Sorted Matrix

  Time: O(n+m) Space: O(1)

• LRU Cache

  Time: O(1) Space: O(n)

• Largest Number

  Time: O(n) Space: O(n)

• Largest Rectangle in Histogram

  Time: O(n) Space: O(n)

• Least Number of Unique Integers after K Removals

  Time: O(n) Space: O(n)

• Letter Combinations of a Phone Number

  Time: O(n) Space: O(n)

• Linked List Cycle II

  Time: O(n) Space: O(1)

• Longest Consecutive Sequence

  Time: O(n) Space: O(n)

• Longest Cycle in Graph

  Time: O(nm) Space: O(nm)

• Longest Increasing Path in a Matrix

  Time: O(4^mn) Space: O(mn)

• Longest Increasing Subsequence

  Time: O(nlogn) Space: O(n)

• Longest Palindromic Substring

  Time: O(n²) Space: O(n²)

• Longest Repeating Character Replacement

  Time: O(n) Space: O(1)

• Longest Substring Without Repeating Characters

  Time: O(n) Space: O(26)

• Longest Substring with at least k repeating characters

  Time: O(n) Space: O(26)

• Lowest Common Ancestor of a Binary Tree

  Time: O(n) Space: O(h)

• Matching Pairs

  Time: O(n) Space: O(n)

• Max Area of Island

  Time: O(nm) Space: O(1)

• Max Consecutive Ones III

  Time: O(n) Space: O(1)

• Max Increase to Keep City Skyline

  Time: O(n²) Space: O(n)

• Maximal Rectangle

  Time: O(nm) Space: O(m)

• Maximal Square

  Time: O(mn) Space: O(mn)

• Maximum Frequency Stack

  Time: O(logn) Space: O(n)

• Maximum Product Subarray

  Time: O(n) Space: O(1)

• Maximum Subarray

  Time: O(n) Space: O(n)

• Maximum Width of Binary Tree

  Time: O(h) Space: O(1)

• Median of Two Sorted Arrays

  Time: O(log(m+n)) Space: O(1)

• Meeting Rooms II

  Time: O(n) Space: O(n)

• Merge k Sorted Lists

  Time: O(n) Space: O(k)

• Min Cost to Connect All Points

  Time: O(1) Space: O(1)

• Minimize Deviation in Array

  Time: O(n) Space: O(n)

• Minimum Cost for Tickets

  Time: O(N) Space: O(N)

• Minimum Remove to Make Valid Parentheses

  Time: O(n) Space: O(n)

• Minimum Size Subarray Sum

  Time: O(n) Space: O(1)

• Minimum Window Substring

  Time: O(n+m) Space: O(n+m)

• Minimum sum partition

  Time: O(n) Space: O(n)

• Multiply Strings

  Time: O(nm) Space: O(nm)

• Next Permutation

  Time: O(n) Space: O(1)

• Number of Islands

  Time: O(mn) Space: O(1)

• Palindrome Partitioning

  Time: O(n2ⁿ) Space: O(n²)

• Palindrome Partitioning II

  Time: O(n²) Space: O(n²)

• Partition Array for Maximum Sum

  Time: O(nk) Space: O(n)

• Partition Equal Subset Sum

  Time: O(n*sum) Space: O(sum)

• Partition Labels

  Time: O(n) Space: O(1)

• Path Sum III

  Time: O(n) Space: O(n)

• Perfect Squares

  Time: O(n²) Space: O(n)

• Permutation Sequence

  Time: O(n) Space: O(n)

• Populating Next Right Pointers in Each Node

  Time: O(h) Space: O(1)

• Predict the Winner

  Time: O(n²) Space: O(n)

• Product of Array Except Self

  Time: O(n) Space: O(1)

• Random Pick with Weight

  Time: O(log n) Space: O(n)

• Reconstruct Itinerary

  Time: O(1) Space: O(V²)

• Recover Binary Search Tree

  Time: O(n) Space: O(1)

• Regular Expression Matching

  Time: O(mn) Space: O(mn)

• Remove Duplicate Letters

  Time: O(n) Space: O(n)

• Remove Duplicates from Sorted List II

  Time: O(n) Space: O(1)

• Remove Invalid Parentheses

  Time: O(2ⁿ) Space: O(n2ⁿ)

• Remove K Digits

  Time: O(n+k) Space: O(n)

• Remove Nth Node From End of List

  Time: O(n) Space: O(1)

• Reorder List

  Time: O(n) Space: O(1)

• Replace Words

  Time: O(nm) Space: O(d)

• Restore IP Addresses

  Time: O(n³) Space: O(1)

• Reverse Linked List II

  Time: O(n) Space: O(1)

• Reverse Nodes in k-Group

  Time: O(n) Space: O(1)

• Rotate Array

  Time: O(logn) Space: O(1)

• Rotate List

  Time: O(n) Space: O(1)

• Rotational Cipher

  Time: O(n) Space: O(1)

• Russian Doll Envelopes

  Time: O(nlogn) Space: O(n)

• Score of Parentheses

  Time: O(n) Space: O(n)

• Scramble String

  Time: O(2ⁿ) Space: O(m+n)

• Search Suggestions System

  Time: O(ns) Space: O(1)

• Search a 2D Matrix

  Time: O(mn) Space: O(1)

• Search in Rotated Sorted Array

  Time: O(n) Space: O(n)

• Search in Rotated Sorted Array II

  Time: O(n) Space: O(1)

• Serialize and Deserialize Binary Tree

  Time: O(n) Space: O(n)

• Set Intersection Size At Least Two

  Time: O(nlogn) Space: O(1)

• Set Matrix Zeroes

  Time: O(n²) Space: O(1)

• Shortest Path in Binary Matrix

  Time: O(1) Space: O(1)

• Simplify Path

  Time: O(n) Space: O(1)

• Single Number II

  Time: O(n) Space: O(1)

• Sliding Window Maximum

  Time: O(n) Space: O(k)

• Sort Colors

  Time: O(n) Space: O(1)

• Sort List

  Time: O(nlogn) Space: O(1)

• Split Array Largest Sum

  Time: O(n²m) Space: O(nm)

• String to Integer Atoi

  Time: O(n) Space: O(1)

• Subarray Sum Equals K

  Time: O(n) Space: O(n)

• Subsets

  Time: O(n2ⁿ) Space: O(n)

• Super Egg Drop

  Time: O(KlogN) Space: O(NK)

• Swap Nodes in Pairs

  Time: O(n) Space: O(1)

• Task Scheduler

  Time: O(n) Space: O(1)

• Text Justification

  Time: O(nm) Space: O(n)

• The Skyline Problem

  Time: O(nlogn) Space: O(n)

• Top K Frequent Elements

  Time: O(nlogn) Space: O(n)

• Trapping Rain Water

  Time: O(n) Space: O(1)

• Valid Number

  Time: O(n) Space: O(1)

• Valid Sudoku

  Time: O(81) Space: O(81)

• Vertical Order Traversal of a Binary Tree

  Time: O(n) Space: O(n)

• Where Will the Ball Fall

  Time: O(nm) Space: O(m)

• Wildcard Matching

  Time: O(n+m) Space: O(m)

• Word Break

  Time: O(n²) Space: O(n)

• Word Break II

  Time: O(2ⁿ) Space: O(n)

• Word Ladder

  Time: O(m²n) Space: O(m²n)

• Word Search

  Time: O(nmw) Space: O(n)

• Word Search II

  Time: O(nm) Space: O(w)

• Zigzag Conversion

  Time: O(n) Space: O(n)