Leetcode LeetCode Algorithms # Title Solution Difficulty 1 TwoSum Java easy 2 Add Two Numbers Java medium 3 Longest Substring Without Repeating Characters Java medium 4 Median of Two Sorted Arrays Java hard 5 Longest Palindromic Substring Java medium 7 Reverse Integer Java medium 8 String to Integer (atoi) Java medium 10 Regular Expression Matching Java hard 11 Container With Most Water Java medium 12 Integer to Roman Java medium 13 Roman to Integer Java easy 14 Longest Common Prefix Java easy 19 Remove Nth Node From End of List Java medium 20 Valid Parentheses Java easy 21 Merge Two Sorted Lists Java easy 22 Generate Parentheses Java medium 26 Remove Duplicates from Sorted Array Java easy 28 Find the Index of the First Occurrence in a String Java medium 36 Valid Sudoku Java medium 53 Maximum Subarray Java medium 58 Length of Last Word Java easy 66 Plus One Java easy 69 Sqrt(x) Java easy 70 Climbing Stairs Java easy 88 Merge Sorted Array Java easy 98 Validate Binary Search Tree Java medium 99 Recover Binary Search Tree Java medium 100 Same Tree Java easy 101 Symmetric Tree Java easy 102 Binary Tree Level Order Traversal Java medium 103 Binary Tree Zigzag Level Order Traversal Java medium 104 Maximum Depth of Binary Tree Java easy 107 Binary Tree Level Order Traversal II Java medium 108 Convert Sorted Array to Binary Search Tree Java easy 110 Balanced Binary Tree Java easy 111 Minimum Depth of Binary Tree Java easy 112 Path Sum Java easy 116 Populating Next Right Pointers in Each Node Java medium 117 Populating Next Right Pointers in Each Node II Java medium 118 Pascal's Triangle Java easy 121 Best Time to Buy and Sell Stock Java easy 122 Best Time to Buy and Sell Stock II Java medium 125 Valid Palindrome Java easy 133 Clone Graph Java medium 136 Single Number Java easy 141 Linked List Cycle I Java easy 142 Linked List Cycle II Java medium 155 Min Stack Java medium 169 Majority Element Java easy 189 Rotate Array Java medium 191 Number of 1 Bits Java easy 198 House Robber Java medium 202 Happy Number Java easy 204 Count Primes Java medium 205 Isomorphic Strings Java easy 206 Reverse Linked List Java easy 207 Course Schedule Java medium 208 Implement Trie (Prefix Tree) Java medium 217 Contains Duplicate Java easy 234 Palindrome Linked List Java easy 237 Delete Node in a Linked List Java medium 242 Valid Anagram Java easy 268 Missing Number Java easy 278 First Bad Version Java easy 283 Move Zeroes Java easy 319 Bulb Switcher Java medium 326 Power of Three Java easy 344 Reverse String Java easy 350 Intersection of Two Arrays II Java easy 384 Shuffle an Array Java medium 387 First Unique Character in a String Java easy 392 Is Subsequence Java easy 409 Longest Palindrome Java easy 412 Fizz Buzz Java easy 424 Longest Repeating Character Replacement Java medium 438 Find All Anagrams in a String Java medium 461 Hamming Distance Java easy 509 Fibonacci Number Java easy 551 Student Attendance Record I Java easy 589 N-ary Tree Preorder Traversal Java easy 695 Max Area of Island Java medium 704 Binary Search Java easy 705 Design HashSet Java easy 706 Design HashMap Java easy 724 Find Pivot Index Java easy 746 Min Cost Climbing Stairs Java easy 844 Backspace String Compare Java easy 876 Middle of the Linked List Java easy 1046 Last Stone Weight Java easy 1480 Running Sum of 1d Array Java easy 1839 Longest Substring Of All Vowels in Order Java medium 1943 Describe the Painting Java medium 2160 Minimum Sum Of Four Digit Number After Splitting Digits Java easy LeetCode Database # Title Solution Difficulty 173 Rank Scores MySQL medium 175 Combine Two Tables MySQL easy 176 Second Highest Salary MySQL medium 183 Customers Who Never Order MySQL easy 185 Department Top Three Salaries MySQL hard 196 Delete Duplicate Emails MySQL easy 197 Rising Temperature MySQL easy 584 Find Customer Referee MySQL easy 589 Customer Placing the Largest of Orders MySQL easy 595 Big Countries MySQL easy 607 Sales Person MySQL easy 608 Tree Node MySQL medium 627 Swap Salary MySQL easy 1141 User Activity for the Past 30 Days I MySQL easy 1148 Article Views I MySQL easy 1484 Group Sold Products By The Date MySql easy 1527 Patients With a Condition MySql easy 1581 Customer Who Visited but Did Not Make Any Transactions MySql easy 1667 Fix Names In A Table MySQL easy 1693 Daily Leads and Partners MySQL easy 1729 Find Followers Count MySQL easy 1757 Recyclable and Low Fat Products MySQL easy 1795 Rearrange Products Table MySQL easy 1873 Calculate Special Bonus MySQL easy 1965 Employees With Missing Information MySQL easy