Interview Prep

LeetCode 75 Study Guide

The ultimate 75-question plan to master Data Structures & Algorithms. Curated by top engineers to cover every essential pattern you need for FAANG interviews.

9 Array/String

# Problem Difficulty Action
1
Merge Strings Alternately
LeetCode #1768
 Easy Solve ↗
2
Greatest Common Divisor of Strings
LeetCode #1071
 Easy Solve ↗
3
Kids With the Greatest Number of Candies
LeetCode #1431
 Easy Solve ↗
4
Can Place Flowers
LeetCode #605
 Easy Solve ↗
5
Reverse Vowels of a String
LeetCode #345
 Easy Solve ↗
6
Reverse Words in a String
LeetCode #151
 Medium Solve ↗
7
Product of Array Except Self
LeetCode #238
 Medium Solve ↗
8
Increasing Triplet Subsequence
LeetCode #334
 Medium Solve ↗
9
String Compression
LeetCode #443
 Medium Solve ↗

4 Two Pointers

# Problem Difficulty Action
10
Move Zeroes
LeetCode #283
 Easy Solve ↗
11
Is Subsequence
LeetCode #392
 Easy Solve ↗
12
Container With Most Water
LeetCode #11
 Medium Solve ↗
13
Max Number of K-Sum Pairs
LeetCode #1679
 Medium Solve ↗

4 Sliding Window

# Problem Difficulty Action
14
Maximum Average Subarray I
LeetCode #643
 Easy Solve ↗
15
Maximum Number of Vowels in a Substring
LeetCode #1456
 Medium Solve ↗
16
Max Consecutive Ones III
LeetCode #1004
 Medium Solve ↗
17
Longest Subarray of 1's After Deleting One
LeetCode #1493
 Medium Solve ↗

2 Prefix Sum

# Problem Difficulty Action
18
Find the Highest Altitude
LeetCode #1732
 Easy Solve ↗
19
Find Pivot Index
LeetCode #724
 Easy Solve ↗

4 Hash Map/Set

# Problem Difficulty Action
20
Find the Difference of Two Arrays
LeetCode #2215
 Easy Solve ↗
21
Unique Number of Occurrences
LeetCode #1207
 Easy Solve ↗
22
Determine if Two Strings Are Close
LeetCode #1657
 Medium Solve ↗
23
Equal Row and Column Pairs
LeetCode #2352
 Medium Solve ↗

3 Stack

# Problem Difficulty Action
24
Removing Stars From a String
LeetCode #2390
 Medium Solve ↗
25
Asteroid Collision
LeetCode #735
 Medium Solve ↗
26
Decode String
LeetCode #394
 Medium Solve ↗

2 Queue

# Problem Difficulty Action
27
Number of Recent Calls
LeetCode #933
 Easy Solve ↗
28
Dota2 Senate
LeetCode #649
 Medium Solve ↗

4 Linked List

# Problem Difficulty Action
29
Delete the Middle Node of a Linked List
LeetCode #2095
 Medium Solve ↗
30
Odd Even Linked List
LeetCode #328
 Medium Solve ↗
31
Reverse Linked List
LeetCode #206
 Easy Solve ↗
32
Maximum Twin Sum of a Linked List
LeetCode #2130
 Medium Solve ↗

6 Binary Tree - DFS

# Problem Difficulty Action
33
Maximum Depth of Binary Tree
LeetCode #104
 Easy Solve ↗
34
Leaf-Similar Trees
LeetCode #872
 Easy Solve ↗
35
Count Good Nodes in Binary Tree
LeetCode #1448
 Medium Solve ↗
36
Path Sum III
LeetCode #437
 Medium Solve ↗
37
Longest ZigZag Path in a Binary Tree
LeetCode #1372
 Medium Solve ↗
38
Lowest Common Ancestor of a Binary Tree
LeetCode #236
 Medium Solve ↗

2 Binary Tree - BFS

# Problem Difficulty Action
39
Binary Tree Right Side View
LeetCode #199
 Medium Solve ↗
40
Maximum Level Sum of a Binary Tree
LeetCode #1161
 Medium Solve ↗

2 Binary Search Tree

# Problem Difficulty Action
41
Search in a Binary Search Tree
LeetCode #700
 Easy Solve ↗
42
Delete Node in a BST
LeetCode #450
 Medium Solve ↗

4 Graphs - DFS

# Problem Difficulty Action
43
Keys and Rooms
LeetCode #841
 Medium Solve ↗
44
Number of Provinces
LeetCode #547
 Medium Solve ↗
45
Reorder Routes to Make All Paths Lead to City Zero
LeetCode #1466
 Medium Solve ↗
46
Evaluate Division
LeetCode #399
 Medium Solve ↗

2 Graphs - BFS

# Problem Difficulty Action
47
Nearest Exit from Entrance in Maze
LeetCode #1926
 Medium Solve ↗
48
Rotting Oranges
LeetCode #994
 Medium Solve ↗

4 Heap / Priority Queue

# Problem Difficulty Action
49
Kth Largest Element in an Array
LeetCode #215
 Medium Solve ↗
50
Smallest Number in Infinite Set
LeetCode #2336
 Medium Solve ↗
51
Maximum Subsequence Score
LeetCode #2542
 Medium Solve ↗
52
Total Cost to Hire K Workers
LeetCode #2462
 Medium Solve ↗

4 Binary Search

# Problem Difficulty Action
53
Guess Number Higher or Lower
LeetCode #374
 Easy Solve ↗
54
Successful Pairs of Spells and Potions
LeetCode #2300
 Medium Solve ↗
55
Find Peak Element
LeetCode #162
 Medium Solve ↗
56
Koko Eating Bananas
LeetCode #875
 Medium Solve ↗

2 Backtracking

# Problem Difficulty Action
57
Letter Combinations of a Phone Number
LeetCode #17
 Medium Solve ↗
58
Combination Sum III
LeetCode #216
 Medium Solve ↗

4 DP - 1D

# Problem Difficulty Action
59
N-th Tribonacci Number
LeetCode #1137
 Easy Solve ↗
60
Min Cost Climbing Stairs
LeetCode #746
 Easy Solve ↗
61
House Robber
LeetCode #198
 Medium Solve ↗
62
Domino and Tromino Tiling
LeetCode #790
 Medium Solve ↗

4 DP - Multidimensional

# Problem Difficulty Action
63
Unique Paths
LeetCode #62
 Medium Solve ↗
64
Longest Common Subsequence
LeetCode #1143
 Medium Solve ↗
65
Best Time to Buy and Sell Stock with Transaction Fee
LeetCode #714
 Medium Solve ↗
66
Edit Distance
LeetCode #72
 Medium Solve ↗

3 Bit Manipulation

# Problem Difficulty Action
67
Counting Bits
LeetCode #338
 Easy Solve ↗
68
Single Number
LeetCode #136
 Easy Solve ↗
69
Minimum Flips to Make a OR b Equal to c
LeetCode #1318
 Medium Solve ↗

2 Trie

# Problem Difficulty Action
70
Implement Trie (Prefix Tree)
LeetCode #208
 Medium Solve ↗
71
Search Suggestions System
LeetCode #1268
 Medium Solve ↗

2 Intervals

# Problem Difficulty Action
72
Non-overlapping Intervals
LeetCode #435
 Medium Solve ↗
73
Minimum Number of Arrows to Burst Balloons
LeetCode #452
 Medium Solve ↗

2 Monotonic Stack

# Problem Difficulty Action
74
Daily Temperatures
LeetCode #739
 Medium Solve ↗
75
Online Stock Span
LeetCode #901
 Medium Solve ↗