third party reference:

• TheAlgorithms/Python
• 19_udacity_dsa
• algoexpert
• henrylin2008
• 02. Algorithms and Data Structures

Algorithms' pivot table (all examples are provided in Python)

Difficulty levels:

• easy
• medium
• hard
• very hard

Categories:

• arrays
• binary search trees
• binary trees
• dynamic programming
• famous algorithms
• graphs
• greedy algorithms
• heaps
• linked lists
• recursion
• searching
• sorting
• stacks
• strings
• tries

№	Algorithm	Difficulty	Category	Time comp.	Space comp.
001	Validate Subsequence	Easy – 1/25	Arrays – 1/24	O(n)	O(1)
002	Two Number Sum	Easy – 2/25	Arrays – 2/24	O(n)	O(n)
003	Sorted Squared Array	Easy – 3/25	Arrays – 3/24	O(n)	O(n)
004	Tournament Winner	Easy – 4/25	Arrays – 4/24	O(n)	O(n)
005	Non-Constructible Change	Easy – 5/25	Arrays – 5/24	O(n*log(n))	O(1)
006	Find Closest Value In BST	Easy – 6/25	BST – 1/10	O(log(n))	O(1)
007	Branch Sums	Easy – 7/25	Binary Trees – 1/10	O(n)	O(n)
008	Node Depths	Easy – 8/25	Binary Trees – 2/10	O(n)	O(h)
009	Depth-first Search	Easy – 9/25	Graphs – 1/11	O(v + e)	O(v)
010	Minimum Waiting Time	Easy – 10/25	Greedy Algorithms – 1/5	O(n*log(n))	O(1)
011	Class Photos	Easy – 11/25	Greedy Algorithms – 2/5	O(n*log(n))	O(1)
012	Tandem Bicycle	Easy – 12/25	Greedy Algorithms – 3/5	O(n*log(n))	O(1)
013	Remove Duplicates From Linked List	Easy – 13/25	Linked List – 1/12	O(n)	O(1)
014	Nth Fibonacci	Easy – 14/25	Recursion – 1/12	O(n)	O(1)
015	Product Sum	Easy – 15/25	Recursion – 2/12	O(n)	O(depth)
016	Binary Search	Easy – 16/25	Searching – 1/7	O(log(n))	O(1)
017	Find Three Largest Numbers	Easy – 17/25	Searching – 2/7	O(n)	O(1)
018	Bubble Sort	Easy – 18/25	Sorting – 1/8	O(n^2)	O(1)
019	Insertion Sort	Easy – 19/25	Sorting – 2/8	O(n^2)	O(1)
020	Selection Sort	Easy – 20/25	Sorting – 3/8	O(n^2)	O(1)
021	Palindrome Check	Easy – 21/25	Strings – 1/14	O(n)	O(1)
022	Caesar Cipher Encryptor	Easy – 22/25	Strings – 2/14	O(n)	O(n)
023	Run-Length Encoding	Easy – 23/25	Strings – 3/14	O(n)	O(n)
024	Generate Document	Easy – 24/25	Strings – 4/14	O(n + m)	O(c)
025	First Non-Repeating Character	Easy – 25/25	Strings – 5/14	O(n)	O(1)
026	River Sizes	Medium – 1/52	Graphs – 2/11	O(wh)	O(wh)
027	Three Number Sum	Medium – 2/52	Arrays – 6/24	O(n^2)	O(1)
028	Smallest Difference	Medium – 3/52	Arrays – 7/24	O(nlog(n) + mlog(m))	O(1)
029	Move Element To End	Medium – 4/52	Arrays – 8/24	O(n)	O(1)
030	Monotonic Array	Medium – 5/52	Arrays – 9/24	O(n)	O(1)
031	Spiral Traverse	Medium – 6/52	Arrays – 10/24	O(n)	O(n)
032	Longest Peak	Medium – 7/52	Arrays – 11/24	O(n)	O(1)
033	Array Of Products	Medium – 8/52	Arrays – 12/24	O(n)	O(n)
034	First Duplicate Value	Medium – 9/52	Arrays – 13/24	O(n)	O(1)
035	Merge Overlapping Intervals	Medium – 10/52	Arrays – 14/24	O(n*log(n))	O(n)
036	BST Construction	Medium – 11/52	BST – 2/10	O(log(n))	O(1)
037	Validate BST	Medium – 12/52	BST – 3/10	O(n)	O(d)
038	BST Traversal	Medium – 13/52	BST – 4/10	O(n)	O(n)
039	Min Height BST	Medium – 14/52	BST – 5/10	O(n)	O(n)
040	Find Kth Largest Value In BST	Medium – 15/52	BST – 6/10	O(h + k)	O(h)
041	Reconstruct BST	Medium – 16/52	BST – 7/10	O(n)	O(h)
042	Invert Binary Tree	Medium – 17/52	Binary Trees – 3/10	O(n)	O(d)
043	Binary Tree Diameter	Medium – 18/52	Binary Trees – 4/10	O(n)	O(n)
044	Find Successor	Medium – 19/52	Binary Trees – 5/10	O(h)	O(1)
045	Height Balanced Binary Tree	Medium – 20/52	Binary Trees – 6/10	O(n)	O(h)
046	Max Subset Sum No Adjacent	Medium – 21/52	Dynamic Programming – 1/19	O(n)	O(1)
047	Number Of Ways To Make Change	Medium – 22/52	Dynamic Programming – 2/19	O(nd)	O(n)
048	Min Number Of Coins For Change	Medium – 22/52	Dynamic Programming – 3/19	O(nd)	O(n)
049	Levenshtein Distance	Medium – 24/52	Dynamic Programming – 4/19	O(nm)	O(min(n, m))
050	Number Of Ways To Traverse Graph	Medium – 25/52	Dynamic Programming – 5/19	O(n + m)	O(1)
051	Kadane's Algorithm	Medium – 26/52	Famous Algorithms – 1/5	O(n)	O(1)
052	Single Cycle Check	Medium – 27/52	Graphs – 2/11	O(n)	O(1)
053	Breadth-first Search	Medium – 28/52	Graphs – 3/11	O(v + e)	O(v)
054	Youngest Common Ancestor	Medium – 29/52	Graphs – 5/11	O(d)	O(1)
055	Remove Islands	Medium – 30/52	Graphs – 6/11	O(wh)	O(wh)
056	Cycle In Graph	Medium – 31/52	Graphs – 7/11	O(v + e)	O(v)
057	Task Assignment	Medium – 32/52	Greedy Algorithms – 4/5	O(n*log(n))	O(n)
058	Valid Starting City	Medium – 33/52	Greedy Algorithms – 5/5	O(n)	O(1)
059	Min Heap Construction	Medium – 34/52	Heaps – 1/5	O(n)	O(1)
060	Linked List Construction	Medium – 35/52	Linked List – 2/12	O(1)	O(1)
061	Remove Nth Node From End	Medium – 36/52	Linked List – 3/12	O(n)	O(1)
062	Sum Of Linked Lists	Medium – 37/52	Linked List – 4/12	O(max(n, m))	O(max(n, m))
063	Permutations	Medium – 38/52	Recursion – 3/12	O(n*n!)	O(n*n!)
064	Powerset	Medium – 39/52	Recursion – 4/12	O(n*2^n)	O(n*2^n)
065	Phone Number Mnemonics	Medium – 40/52	Recursion – 5/12	O(4^n * n)	O(4^n * n)
066	Staircase Traversal	Medium – 41/52	Recursion – 6/12	O(n)	O(n)
067	Search In Sorted Matrix	Medium – 42/52	Searching – 3/7	O(n + m)	O(1)
068	Three Number Sort	Medium – 43/52	Sorting – 4/8	O(n)	O(1)
069	Min Max Stack Construction	Medium – 44/52	Stacks – 1/6	O(1)	O(1)
070	Balanced Brackets	Medium – 45/52	Stacks – 2/6	O(n)	O(n)
071	Sunset Views	Medium – 46/52	Stacks – 3/6	O(n)	O(n)
072	Sort Stack	Medium – 47/52	Stacks –
073	Longest Palindromic Substring	Medium – 48/52	Strings – 6/14	O(n^2)	O(1)
074	Group Anagrams	Medium – 49/52	Strings – 7/14	O(w * n * log(n))	O(wn)
075	Valid IP Addresses	Medium – 50/52	Strings – 8/14	O(1)	O(1)
076	Reverse Words In String	Medium – 51/52	Strings – 9/14	O(n)	O(n)
077	Suffix Trie Construction	Medium – 52/52	Tries – 1/2	O(n^2)	O(n^2)
078	Shift Linked List	Hard – 1/46	Linked List – 8/13	O(n)	O(1)
079	Four Number Sum	Hard – 2/46	Arrays – 15/24	O(n^2)	O(n^2)
080	Subarray Sort	Hard – 3/46	Arrays – 16/24	O(n)	O(1)
081	Largest Range	Hard – 4/46	Arrays – 17/24	O(n)	O(n)
082	Min Rewards	Hard – 5/46	Arrays – 18/24	O(n)	O(n)
083	Zigzag Traverse	Hard – 6/46	Arrays – 19/24	O(n)	O(n)
084	Same BSTs	Hard – 7/46	BST – 8/10	O(n^2)	O(d)
085	Validate Three Nodes	Hard – 8/46	BST – 9/10	O(h)	O(1)
086	Max Path Sum	Hard – 9/46	Binary Trees – 7/12	O(n)	O(log(n))
087	Find Nodes Distance K	Hard – 10/46	Binary Trees – 8/12	O(n)	O(n)
088	Max Sum Increasing Subsequence	Hard – 11/46	Dynamic Programming – 6/19	O(n^2)	O(n)
089	Longest Common Subsequence	Hard – 12/46	Dynamic Programming – 7/19	O(nm)	O(nm)
090	Min Number Of Jumps	Hard – 13/46	Dynamic Programming – 8/19	O(n)	O(1)
091	Water Area	Hard – 14/46	Dynamic Programming – 9/19	O(n)	O(n)
092	Knapsack Problem	Hard – 15/46	Dynamic Programming – 10/19	O(nc)	O(nc)
093	Disk Stacking	Hard – 16/46	Dynamic Programming – 11/19	O(n^2)	O(n)
094	Numbers In Pi	Hard – 17/46	Dynamic Programming – 12/19	O(n^3 + m)	O(n + m)
095	Maximum Sum Submatrix	Hard – 18/46	Dynamic Programming – 13/19	O(w * h)	O(w * h)
096	Maximize Expression	Hard – 19/46	Dynamic Programming – 14/19
097	Dijkstra's Algorithm	Hard – 20/46	Famous Algorithms – 2/5	O((v + e) * log(v))	O(v)
098	Topological Sort	Hard – 21/46	Famous Algorithms – 3/5	O(j + d)	O(j + d)
099	Boggle Board	Hard – 22/46	Graphs – 8/11	O(nm*8^s + ws)	O(nm + ws)
100	Continuous Median	Hard – 23/46	Heaps – 2/5	O(log(n))	O(n)
101	Sort K-Sorted Array	Hard – 24/46	Heaps – 3/5	O(nlog(k))	O(k)
102	Laptop Rentals	Hard – 25/46	Heaps – 4/5	O(nlog(n))	O(n)
103	Find Loop	Hard – 26/46	Linked List – 5/12	O(n)	O(1)
104	Reverse Linked List	Hard – 27/46	Linked List – 6/12	O(n)	O(1)
105	Merge Linked Lists	Hard – 28/46	Linked List – 7/12	O(n + m)	O(1)
106	Lowest Common Manager	Hard – 29/46	Recursion – 7/12	O(n)	O(d)
107	Interweaving Strings	Hard – 30/46	Recursion – 8/12	O(nm)	O(nm)
108	Solve Sudoku	Hard – 31/46	Recursion – 9/12	O(1)	O(1)
109	Generate Div Tags	Hard – 32/46	Recursion – 10/12	O((2n)!/((n!((n + 1)!))))	O((2n)!/((n!((n + 1)!))))
110	Ambiguous Measurements	Hard – 33/46	Recursion – 11/12	O(low * high * n)	O(low * high)
111	Shifted Binary Search	Hard – 34/46	Searching – 4/7	O(log(n))	O(1)
112	Quickselect	Hard – 35/46	Searching – 5/7	O(n)	O(1)
113	Index Equals Value	Hard – 36/46	Searching – 6/7	O(log(n))	O(1)
114	Quick Sort	Hard – 37/46	Sorting – 5/9	O(n*log(n))	O(log(n))
115	Heap Sort	Hard – 38/46	Sorting – 6/9	O(n*log(n))	O(1)
116	Radix Sort	Hard – 39/46	Sorting – 7/9
117	Shorten Path	Hard – 40/46	Stacks – 6/7	O(n)	O(n)
118	Largest Rectangle Under Skyline	Hard – 41/46	Stacks – 7/7	O(n)	O(n)
119	Longest Substring Without Duplication	Hard –	Strings –	O(n)	O(min(n, a))
120	Underscorify Substring	Hard –	Strings –	O(n * m)	O(n)
121	Pattern Matcher	Hard –	Strings –	O(n^2 + m)	O(n + m)
122	Multi String Search	Hard –	Tries –	O(ns + bs)	O(ns)