Problem Sets | Design Gurus

Core Pillars

Patterns

Algorithms

Data Structures

two pointers

fast and slow pointers

sliding window

merge intervals

cyclic sort

linked list reversal

stack

monotonic stack

hash map

level order traversal

tree breadth first search

tree depth first search

graph

matrix traversal

two heaps

subsets

modified binary search

top k elements

k-way merge

greedy algorithm

backtracking

topological sort

union-find

prefix sum

counting

simulation

#	Title	Acceptance	Difficulty
1	Contains Duplicate (easy) array hash set counting +1 more	62.7%	easy
2	Pangram (easy) string hash set counting	14.3%	easy
3	Reverse Vowels (easy) two pointers string array +1 more	77.8%	easy
4	Valid Palindrome (easy)	0.0%	easy
5	Valid Anagram (easy)	0.0%	easy
6	Shortest Word Distance (easy)	0.0%	easy
7	Number of Good Pairs (easy)	0.0%	easy
8	Sqrt (medium) binary search modified binary search	0.0%	Med.
9	Pair with Target Sum (easy) two pointers array binary search +1 more	100.0%	easy
10	Find Non-Duplicate Number Instances (easy) two pointers array sorting	0.0%	easy
11	Squaring a Sorted Array (easy) two pointers array sorting	0.0%	easy
12	Triplet Sum to Zero (medium) two pointers sorting array +1 more	0.0%	Med.
13	Triplet Sum Close to Target (medium) two pointers sorting array	0.0%	Med.
14	Triplets with Smaller Sum (medium) two pointers array sorting +1 more	0.0%	Med.
15	Subarrays with Product Less than a Target (medium) array sliding window two pointers	0.0%	Med.
16	Dutch National Flag Problem (medium) two pointers sorting array	0.0%	Med.
17	Problem Challenge 1: Quadruple Sum to Target (medium) two pointers sorting array	0.0%	Med.
18	Problem Challenge 2: Comparing Strings containing Backspaces (medium)	0.0%	Med.
19	Problem Challenge 3: Minimum Window Sort (medium)	0.0%	Med.
20	LinkedList Cycle (easy) linked list fast and slow pointers two pointers	0.0%	easy
21	Middle of the LinkedList (easy)	0.0%	easy
22	Start of LinkedList Cycle (medium)	0.0%	Med.
23	Happy Number (medium)	0.0%	Med.
24	Problem Challenge 1: Palindrome LinkedList (medium)	0.0%	Med.
25	Problem Challenge 2: Rearrange a LinkedList (medium)	0.0%	Med.
26	Problem Challenge 3: Cycle in a Circular Array (hard)	0.0%	hard
27	Maximum Sum Subarray of Size K (easy) sliding window array prefix sum +1 more	0.0%	easy
28	Smallest Subarray With a Greater Sum (easy)	0.0%	easy
29	Longest Substring with K Distinct Characters (medium)	0.0%	Med.
30	Fruits into Baskets (medium)	0.0%	Med.
31	Longest Substring with Same Letters after Replacement (hard)	0.0%	hard
32	Longest Subarray with Ones after Replacement (hard)	0.0%	hard
33	Problem Challenge 1: Permutation in a String (hard)	0.0%	hard
34	Problem Challenge 2: String Anagrams (hard)	0.0%	hard
35	Problem Challenge 3: Smallest Window containing Substring (hard)	0.0%	hard
36	Problem Challenge 4: Words Concatenation (hard)	0.0%	hard
37	Merge Intervals (medium) merge intervals sorting array +1 more	0.0%	Med.
38	Insert Interval (medium)	0.0%	Med.
39	Intervals Intersection (medium)	0.0%	Med.
40	Conflicting Appointments (medium)	0.0%	Med.
41	Problem Challenge 1: Minimum Meeting Rooms (hard)	0.0%	hard
42	Problem Challenge 2: Maximum CPU Load (hard)	0.0%	hard
43	Problem Challenge 3: Employee Free Time (hard)	0.0%	hard
44	Cyclic Sort (easy) cyclic sort sorting array	0.0%	easy
45	Find the Missing Number (easy)	0.0%	easy
46	Find all Missing Numbers (easy)	0.0%	easy
47	Find the Duplicate Number (easy)	0.0%	easy
48	Find all Duplicate Numbers (easy)	0.0%	easy
49	Problem Challenge 1: Find the Corrupt Pair (easy)	0.0%	easy
50	Problem Challenge 2: Find the Smallest Missing Positive Number (medium)	0.0%	Med.
51	Problem Challenge 3: Find the First K Missing Positive Numbers (hard)	0.0%	hard
52	Reverse a LinkedList (easy) linked list linked list reversal two pointers +1 more	0.0%	easy
53	Reverse a Sub-list (medium)	0.0%	Med.
54	Reverse every K-element Sub-list (medium)	0.0%	Med.
55	Problem Challenge 1: Reverse alternating K-element Sub-list (medium)	0.0%	Med.
56	Problem Challenge 2: Rotate a LinkedList (medium)	0.0%	Med.
57	Remove Nodes From Linked List (medium) linked list linked list reversal stack +2 more	0.0%	Med.
58	Remove All Adjacent Duplicates In String (easy)	0.0%	easy
59	Next Greater Element (easy)	0.0%	easy
60	Daily Temperatures (easy)	0.0%	easy
61	Remove All Adjacent Duplicates in String II (medium)	0.0%	Med.
62	Remove K Digits (hard)	0.0%	hard
63	Problem 1: First Non-repeating Character (easy)	0.0%	easy
64	Solution: First Non-repeating Character (easy)	0.0%	easy
65	Problem 2: Largest Unique Number (easy)	0.0%	easy
66	Solution: Largest Unique Number (easy)	0.0%	easy
67	Problem 3: Maximum Number of Balloons (easy)	0.0%	easy
68	Solution: Maximum Number of Balloons (easy)	0.0%	easy
69	Problem 4: Longest Palindrome(easy)	0.0%	easy
70	Solution: Longest Palindrome(easy)	0.0%	easy
71	Problem 5: Ransom Note (easy)	0.0%	easy
72	Solution: Ransom Note (easy)	0.0%	easy
73	Binary Tree Level Order Traversal (easy) level order traversal tree breadth first search binary tree +2 more	0.0%	easy
74	Reverse Level Order Traversal (easy)	0.0%	easy
75	Zigzag Traversal (medium)	0.0%	Med.
76	Level Averages in a Binary Tree (easy)	0.0%	easy
77	Minimum Depth of a Binary Tree (easy)	0.0%	easy
78	Level Order Successor (easy)	0.0%	easy
79	Connect Level Order Siblings (medium)	0.0%	Med.
80	Problem Challenge 1: Connect All Level Order Siblings (medium)	0.0%	Med.
81	Problem Challenge 2: Right View of a Binary Tree (easy) binary tree tree breadth first search level order traversal +1 more	0.0%	easy
82	Binary Tree Path Sum (easy) binary tree tree depth first search recursion	0.0%	easy
83	All Paths for a Sum (medium)	0.0%	Med.
84	Sum of Path Numbers (medium)	0.0%	Med.
85	Path With Given Sequence (medium)	0.0%	Med.
86	Count Paths for a Sum (medium)	0.0%	Med.
87	Problem Challenge 1: Tree Diameter (medium) binary tree tree depth first search recursion	0.0%	Med.
88	Problem Challenge 2: Path with Maximum Sum (hard)	0.0%	hard
89	Problem 1: Find if Path Exists in Graph(easy)	0.0%	easy
90	Solution: Find if Path Exists in Graph(easy)	0.0%	easy
91	Problem 2: Number of Provinces (medium)	0.0%	Med.
92	Problem 3: Minimum Number of Vertices to Reach All Nodes(medium)	0.0%	Med.
93	Solution: Minimum Number of Vertices to Reach All Nodes(medium)	0.0%	Med.
94	Number of Islands (easy) matrix traversal graph matrix +3 more	0.0%	easy
95	Biggest Island (easy) matrix graph algorithms depth-first search +3 more	100.0%	easy
96	Flood Fill (easy) matrix traversal recursion matrix +2 more	0.0%	easy
97	Number of Closed Islands (easy) matrix graph algorithms matrix traversal +3 more	0.0%	easy
98	Problem Challenge 1 (easy)	0.0%	easy
99	Problem Challenge 2 (medium)	0.0%	Med.
100	Problem Challenge 3 (medium)	0.0%	Med.