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Leetcode 75

I have already completed a basic data structures and algorithms course. I decided to continue with Leetcode 75, which is a curated list of 75 essential problems divided into 22 categories, so I can properly memorize them through practice.


  • Array / String
    1. Merge Strings Alternatively
    2. Greatest Common Divisor of Strings
    3. Kids With the Greatest Number of Candies
    4. Can Place Flowers
    5. Reverse Vowels of a String
    6. Reverse Words in a String
    7. Product of Array Except Self
    8. Increasing Triplet Subsequence
    9. String Compression

  • Two pointers
    1. Move Zeroes
    2. Is Subsequence
    3. Container With Most Water
    4. Max Number of K-Sum Pairs

  • Sliding Window
    1. Maximum Average Subarray I
    2. Maximum Number of Vowels in a Substring of Given Length
    3. Max Consecutive Ones III
    4. Longest Subarray of 1's After Deleting One Element

  • Prefix Sum
    1. Find the Highest Altitued
    2. Find Pivot Index

  • Hash Map / Set
    1. Find the Difference of Two Arrays
    2. Unique Number of Occurences
    3. Determine If Two Strins Are Close
    4. Equal Row and Column Pairs

  • Stack
    1. Removing Stars From a String
    2. Asteroid Collision
    3. Decode String

  • Queue
    1. Number of Recent Calls
    2. Dota2 Senate

  • Linked List
    1. Delete the Middle Node of a Linked List
    2. Odd Even Linked List
    3. Reverse Linked List
    4. Maximum Twin Sum of a Linked List

  • Binary Tree – DFS
    1. Maximum Depth of Binary Tree
    2. Leaf-Similar Trees
    3. Count Good Nodes in Binary Tree
    4. Path Sum III
    5. Longest ZigZag Path in a Binary Tree

  • Binary Tree – BFS
    1. Binary Tree Right Side View
    2. Maximum Level Sum of a Binary Tree

  • Binary Search Tree
    1. Search in a Binary Search Tree
    2. Delete Node in a BST

  • Graphs – DFS
    1. Keys and Rooms
    2. Number of Provinces
    3. Reorder Routes to Make All Paths Lead to the City Zero
    4. Evaluate Division

  • Graphs – BFS
    1. Nearest Exist from Entrance in Maxe
    2. Rotting Oranges

  • Heap / Priority Queue
    1. Kth Largest Element in an Array
    2. Smallest Number in Infinite Set
    3. Maximum Subsequence Score
    4. Total Cost to Hire K Workers

  • Binary Search
    1. Guess Number Higher or Lower
    2. Successful Pairs of Spells and Potions
    3. Find Peak Element
    4. Koko Eating Bananas

  • Backtracking
    1. Letter Combinations of a Phone Number
    2. Combination Sum III

  • DP – 1D
    1. N-th Tribonacci Number
    2. Min Cost Climbing Stairs
    3. House Robber
    4. Domino and Tromino Tiling

  • DP – Multimensional
    1. Unique Paths
    2. Longest Common Subsequence
    3. Best Time to Buy and Sell Stock with Transaction Fee
    4. Edit Distance

  • Bit Manipulation
    1. Counting Bits
    2. Single Number
    3. Minimum Flips to Make a OR b Equal to c

  • Trie
    1. Implement Trie (Prefix Tree)
    2. Search Suggestion System

  • Intervals
    1. Non-overlapping Intervals
    2. Minimum Number of Arrows to Burst Balloons

  • Monotonic Stack
    1. Daily Temperatures
    2. Online Stock Span