Daily Coding Problem

My solutions for programming problems from https://www.dailycodingproblem.com/

If you are looking to help out a fellow programmer, please head over to the Issues Section.

Problem Legend

Problem ID	Problem	Asked by	Solved status	Solved in
1	2-Sum problem	Google	Solved	Python, C++, Java
2	Product except self	Uber	Solved	Python, C++
3	Serialize and Deserialize Binary Trees	Google	Solved	Python, C++
4	First missing positive	Stripe	Solved	Python, C++
5	car, cdr, cons	Jane Street	Solved	Python, C++
6	XOR Linked list	Google	Solved	C++
7	Number of ways to decode a message	Facebook	Solved	Python, C++
8	Universal Value Tree Count	Google	Solved	Python, C++
9	Largest sum of non-adjacent numbers in array	Airbnb	Solved	Python, C++
10	Job Scheduler	Apple	Solved	Python, C++
11	Autocomplete system	Twitter	Solved	Python, C++
12	Number of ways to climb a staircase	Amazon	Solved	Python
13	Longest substring with at most K distinct characters	Amazon	Solved	Python
14	Pi estimation using Monte Carlo method	Google	Solved	Python
15	Random element from large input stream	Facebook	Solved	Python
16	Order Log	Twitter	Solved	Python
17	Longest absolute path in file structure	Google	Solved	Python
18	Max of each Subarray	Google	Solved	Python
19	House paint problem	Facebook	Solved	Java
20	Intersecting Linked Lists	Google	Solved	Python
21	Classroom Scheduling problem	Snapchat	Solved	Python
22	Word Break	Microsoft	Solved	Python
23	Number of ways to go from A to B	Google	Unsolved
24	Binary Tree Locking	Google	Solved	Python
25	Regular Expression Implementation	Facebook	Unsolved
26	Remove kth last element in linked list	Google	Solved	Python
27	Balanced parantheses	Facebook	Unsolved
28	Justify text	Palantir	Solved	Python
29	Run length encoding	Amazon	Solved	Python
30	Elevation map	Facebook	Solved	Python, C++
31	Minimum edit distance between two strings	Google	Unsolved
32	Currency Exchange	Jane Street	Unsolved
33	Running Median	Microsoft	Solved	Python
34	Minimum insertion palindrome	Quora	Unsolved
35	Swap RGB array in-place	Google	Solved	Python
36	Second largest node in binary tree	Dropbox	Solved	Python
37	Power Set	Google	Solved	Python
38	Non-threatening Queens	Microsoft	Solved	Python
39	Conway's Game of Life	Dropbox	Unsolved
40	Non-duplicated item in array	Google	Solved	Python
41	Flight itinerary	Facebook	Solved	Python
42	K sum subset	Google	Solved	Python
43	Stack Implementation	Amazon	Solved	Python
44	Count inversions	Google	Solved	Python
45	Random number generator	Two Sigma	Solved	Python
46	Longest palindromic substring	Amazon	Solved	Python
47	Maximum stock profit	Facebook	Solved	Python
48	Reconstruct binary tree given preorder and postorder traversals	Google	Solved	Python
49	Max Sum Subarray or Kadane's algorithm	Amazon	Solved	Python
50	Binary Tree Arithmetic	Microsoft	Solved	Python, C++
51	Deck shuffling with swaps only	Facebook	Solved	Python
52	LRU Cache Implementation	Google	Solved	Python
53	Queue Implementation	Apple	Solved	Python
54	Sudoku solver	Dropbox	Solved	Python
55	URL shortener	Microsoft	Solved	Python
56	Graph Coloring	Google	Solved	Python
57	String Break	Amazon	Solved	Python
58	Rotated sorted array search	Amazon	Solved	Python
59	File Syncing between two computers	Google	Unsolved
60	Equal Sum Partition	Facebook	Solved	Python
61	Integer exponentiation	Google	Solved	Python
62	Top-Left to Bottom-Right	Facebook	Solved	Python
63	Word Matrix	Microsoft	Solved	Python
64	Knight's Tour	Google	Solved	Python
65	Spiral Matrix	Amazon	Solved	Python
66	Unbiased Toss	Square	Solved	Python
67	LFU Cache Implementation	Google	Solved	Python
68	Attacking Bishops	Google	Solved	Python
69	Max triplet product	Facebook	Solved	Python
70	Perfect Numbers	Microsoft	Solved	Python
71	Another Random Number Generator	Microsoft	Solved	Python
72	Largest Value Path in a Directed Graph	Google	Solved	Python
73	Reverse Linked List in-place	Google	Solved	Python
74	Count occurrences in multiplication table	Apple	Solved	Python
75	Largest increasing subsequence	Microsoft	Solved	Python
76	Lexicographic matrix sort	Google	Solved	Python
77	Merge overlapping intervals	Snapchat	Solved	Python
78	Mergesort linked lists	Google	Solved	Python
79	Modifiabale non-decreasing array	Facebook	Solved	Python
80	Deepest Node in Binary Tree	Google	Solved	Python, C++
81	Letter Combinations from Dictionary	Yelp	Solved	Python
82	Implementation of readN(n) using read7	Microsoft	Solved	Python
83	Reverse Binary Tree	Google	Solved	Python
84	Island Count	Amazon	Solved	Python
85	X or Y	Facebook	Solved	Python
86	Min parantheses removal	Google	Solved	Python
87	Validate Map	Uber	Solved	Python
88	Integer division	ContextLogic	Solved	Python
89	Valid BST	LinkedIn	Solved	Python
90	Random number generator with exception rule	Google	Solved	Python
91	Function correction	Dropbox	Solved	Python
92	Valid Course Ordering	Airbnb	Solved	Python
93	Largest BST Size	Apple	Solved	Python
94	Tree Maximum Path Sum between 2 Leaves	Google	Solved	Python
95	Next greater permutation	Palantir	Solved	Python
96	All permutations	Microsoft	Solved	Python
97	Time-based Map	Stripe	Solved	Python
98	Find Word in Grid	Coursera	Solved	Python
99	Longest Continuous Sequence	Microsoft	Solved	Python
100	Minimum Step Move	Google	Solved	Python
101	Goldbach conjecture	Alibaba	Solved	Python, C++
102	Continuous subarray sum equals K	Lyft	Solved	Python
103	Shortest substring containing given characters	Square	Solved	Python
104	Palindrome Linked List	Google	Solved	Python
105	Function Debounce	Facebook	Solved	Python
106	Hop array to other end	Pinterest	Solved	Python, C++
107	Print binary tree level-wise	Microsoft	Solved	Python, C++
108	String shift and check equality	Google	Solved	Python
109	Swap even and odd bits	Cisco	Solved	Python
110	All paths in a binary tree	Facebook	Solved	Python
111	Anagram start-indices in a string	Google	Solved	Python
112	LCA of Binary Tree	Twitter	Solved	Python, C++
113	Reverse words in a string	Google	Solved	Python, C++
114	Reverse words in string with delimiters relative order	Facebook	Solved	Python, C++
115	Check whether one binary tree is subtree of another	Google	Solved	C++
116	Generate arbitrarily sized binary tree	Jane Street	Solved	C++
117	Max Level sum in a binary tree	Facebook	Solved	C++
118	Sort squares of elements in sorted array	Google	Solved	C++
120	Singleton pattern with twist	Microsoft	Solved	Python
121	Make palindrome with minimum deletions	Google	Solved	C++, Python
122	Collect maximum coins in 2-D matrix	Zillow	Solved	C++, Python
123	Does string represent a number	LinkedIn	Solved	C++
124	Flip coins till only one remains	Microsoft	Solved	C++
125	2-Sum problem in binary tree	Google	Solved	C++
126	Rotate array in-place	Facebook	Solved	C++
127	Add numbers represented as linked list	Microsoft	Solved	C++
128	Tower of Hanoi		Solved	C++
129	Square root of a real number		Solved	C++
130	Maximum profit from k buy-sells	Facebook	Solved	C++
131	Deep clone linked list having a random pointer at each node	Snapchat	Solved	C++
132	Hit Counter class implementation	Riot Games	Solved	C++
133	In-Order successor of a node in a binary tree	Amazon	Solved	C++
134	Large sparse array data structure	Facebook	Solved	C++
135	Min root to leaf sum path in binary tree	Apple	Solved	C++
136	Largest rectangle in a matrix	Google	Solved	C++
137	Bit array implementation	Amazon	Solved	C++
138	Minimum coins for n cents	Google	Solved	C++
139	Peekable iterator	Google	Solved	Python
140	Which two elements occur once in array	Facebook	Solved	C++
141	3 stacks implementation	Microsoft	Solved	C++
142	Balanced parantheses - II	Google
143	List partitioning	Amazon	Solved	C++
144	Nearest larger number in an array	Google	Solved	C++
145	Pairwise swap linked list nodes	Google	Solved	C++
146	Binary tree pruning	BufferBox	Solved	C++
147	Pancake Sort		Solved	C++
148	Subarray sum	Goldman Sachs	Solved	C++
149	Gray code	Apple	Solved	C++
150	K nearest neighbors	LinkedIn	Solved	C++
151	Color image		Solved	C++
152	Random number generator	Triplebyte	Solved	C++
153	Minimum word distance		Solved	C++
154	Stack implementation using heap API	Amazon	Solved	C++
155	Majority Element	MongoDB	Solved	C++
156	smallest number of squared integers which sum to n	Facebook	Solved	C++
157	Palindrome string permutation possible	Amazon	Solved	C++
158	Walled fort		Solved	C++
159	First recurring character in string	Google	Solved	C++
160	Longest path in tree	Uber
161	Reverse bits	Facebook	Solved	C++
162	Shortest unique prefix	Square
163	Reverse Polish notation	Jane Street	Solved	C++
164	Find the only duplicate in array	Google	Solved	C++
165	Number of smaller elements to the right in an array	Google	Solved	C++
166	2-D iterator class	Uber	Solved	C++
167	Palindrome concatenation pairs	Airbnb	Solved	C++
168	Rotate 2-D array in-place	Facebook	Solved	C++
169	Sort a linked list	Google	Solved	C++
170	Shortest transformation from start word to end word	Facebook
171	Busiest time interval from a register	Amazon	Solved	C++
172	Starting indices of word concatenations in a string	Dropbox
173	Flatten a nested dictionary	Stripe	Solved	Python
174	Polymorphism examples	Microsoft	Solved	C++
175	Markov chain simulation	Google	Solved	C++
176	One-to-one character mapping between two strings	Bloomberg	Solved	C++
177	Rotate a linked list	Airbnb	Solved	C++
178	Dice Simulation	Two Sigma	Solved	C++
179	Recover BST from its postorder traversal	Google	Solved	C++
180	Interleave two halves of a stack using a queue	Google	Solved	C++
181	Minimum number of palindromes in a string	Google
182	Minimally connected graph	Facebook	Solved	C++
183	What happens when you type a URL	Twitch	Solved	NA
184	Calculate GCD of numbers	Amazon	Solved	C++
185	Calculate intersection area	Google	Solved	C++
186	Divide array into 2 subsets with min difference of subset sums	Microsoft
187	Overlapping rectangles	Google	Solved	C++
188	Array of functions	Google	Solved	C++
189	Longest contiguous distinct subarray	Google	Solved	C++
190	Max sum subarray of circular array	Facebook	Solved	C++
191	Min intervals to remove to make them non-overlapping	Stripe	Solved	C++
192	Try to reach end of array with array value-sized hops	Google
193	Max profit in a stock price array with a fixed transaction fee	Affirm
194	Number of intersections between line segments joining two sets of n points of parallel lines	Facebook	Solved	C++
195	Count elements between two numbers in a 2-D array	Google	Solved	C++
196	Most frequent subtree sum	Apple	Solved	C++
197	Rotate array to the right by K in-place	Amazon	Solved	C++
198	Largest set of non-coprime numbers in a set	Google	Solved	C++
199	Balanced parantheses - III	Facebook
200	Find a stabbing point between n intervals	Microsoft
201	Maximum sum path in a triangular array	Google
202	Integer palindrome	Palantir	Solved	C++
203	Minimum element in rotated sorted array in faster than linear time	Uber	Solved	C++
204	Count the number of nodes in a complete binary tree in faster than linear time	Amazon	Solved	C++
205	Given a number find the next permutation of it	IBM	Solved	C++
206	Apply a permutation on an array	Twitter	Solved	C++
207	Check if a graph is bipartite	Dropbox
208	Partition a linked list by a node such that all elements >= a node come after those smaller	LinkedIn	Solved	C++
209	Longest common subsequence of 3 strings	YouTube
210	Collatz conjecture verificity and longest sequence	Apple	Solved	C++
211	All starting positions of a pattern in a string	Microsoft	Solved	C++
212	Excel column encoding of a positive integer	Dropbox	Solved	C++
213	Valid IP address combinations from a string	Snapchat	Solved	C++
214	Max continuous ones in binary representation of a number	Stripe	Solved	C++
291	Minimum boats to rescue	Glassdoor	Solved	C++
294	Min Running Track Path	Square	Solved	C++
295	Pascal's Triangle	Stitch Fix	Solved	C++
296	Convert sorted array to Balanced BST	Etsy	Solved	C++
297	Minimum drinks to satisfy preferences	Amazon	Solved	C++
298	Max Run with at most two discrete elements	Google	Solved	C++
299	Min pipe length required for a city graph	Samsung	Solved	C++
311	Peak element in array in O(log N) time	Sumo Logic	Solved	C++