DCP-Solutions

This repository is a collection of solutions for Daily Coding Problem problems.
"A daily coding problem a day keeps the unemployment away..."

Authors

• Madeline Moore - mcmoore11
  • told Peter about the DCPs... he had already been subscribed for over a year
  • managed all folders
• Peter Zhang - PeterTheAmazingAsian
  • made the readme lol
  • subcribed to DCP for way too long

Solutions

Below we have a table of all the DCPs (1-399). The table contains the question number/day, the company that asked the question, a brief description, difficulty, and a link to goto the corresponding folder. There are also two additional columns to show who has completed which problems and in which languages.

Day	Company	Description	Difficulty	Madeline	Peter	Link
001	Google	Given a list of numbers and a number k, return whether any two numbers from the list add up to k.	Easy	Python	C++, Python	go
002	Uber	Given an array of integers, return a new array such that each element at index i of the new array is the product of all the numbers in the original array except the one at i.	Hard	Python	C++, Python	go
003	Google	Given the root to a binary tree, implement serialize(root), which serializes the tree into a string, and deserialize(s), which deserializes the string back into the tree.	Medium	-	C++, Python	go
004	Stripe	Given an array of integers, find the first missing positive integer in linear time and constant space. In other words, find the lowest positive integer that does not exist in the array. The array can contain duplicates and negative numbers as well.	Hard	-	C++, Python	go
005	Jane Street	Implement car and cdr. cons(a, b) constructs a pair, and car(pair) and cdr(pair) returns the first and last element of that pair.	Medium	-	C++, Python	go
006	Google	Implement an XOR linked list; it has an add(element) which adds the element to the end, and a get(index) which returns the node at index.	Hard	-	C++	go
007	Facebook	Given the mapping a = 1, b = 2, ... z = 26, and an encoded message, count the number of ways it can be decoded.	Medium	-	-	go
008	Google	Given the root to a binary tree, count the number of unival subtrees.	Easy	-	C++	go
009	Airbnb	Given a list of integers, write a function that returns the largest sum of non-adjacent numbers. Numbers can be 0 or negative.	Hard	-	-	go
010	Apple	Implement a job scheduler which takes in a function f and an integer n, and calls f after n milliseconds.	Medium	-	-	go
011	Twitter	Implement an autocomplete system. That is, given a query string s and a set of all possible query strings, return all strings in the set that have s as a prefix.	Medium	-	C++	go
012	Amazon	There exists a staircase with N steps, and you can climb up either 1 or 2 steps at a time. Given N, write a function that returns the number of unique ways you can climb the staircase. The order of the steps matters.	Hard	-	C++	go
013	Amazon	Given an integer k and a string s, find the length of the longest substring that contains at most k distinct characters.	Hard	-	-	go
014	Google	The area of a circle is defined as πr^2. Estimate π to 3 decimal places using a Monte Carlo method.	Medium	-	C++	go
015	Facebook	Given a stream of elements too large to store in memory, pick a random element from the stream with uniform probability.	Medium	-	-	go
016	Twitter	You run an e-commerce website and want to record the last N order ids in a log. Implement a data structure to accomplish this	Easy	-	-	go
017	Google	Given a string representing the file system in the above format, return the length of the longest absolute path to a file in the abstracted file system. If there is no file in the system, return 0.	Hard	-	-	go
018	Google	Given an array of integers and a number k, where 1 <= k <= length of the array, compute the maximum values of each subarray of length k.	Hard	-	-	go
019	Facebook	Goal of minimizing cost while ensuring that no two neighboring houses are of the same color. Given an N by K matrix where the nth row and kth column represents the cost to build the nthhouse with kth color, return the minimum cost which achieves this goal.	Medium	-	-	go
020	Google	Given two singly linked lists that intersect at some point, find the intersecting node. The lists are non-cyclical.	Easy	-	-	go
021	Snapchat	Given an array of time intervals (start, end) for classroom lectures (possibly overlapping), find the minimum number of rooms required.	Easy	-	-	go
022	Microsoft	Given a dictionary of words and a string made up of those words (no spaces), return the original sentence in a list.	Medium	-	C++	go
023	Google	You are given an M by N matrix consisting of booleans that represents a board. Each True boolean represents a wall. Each False boolean represents a tile you can walk on. Given this matrix, a start coordinate, and an end coordinate, return the minimum number of steps required to reach the end coordinate from the start.	Easy	-	-	go
024	Google	Implement locking in a binary tree. A binary tree node can be locked or unlocked only if all of its descendants or ancestors are not locked.	Medium	-	C++	go
025	Facebook	Implement regular expression matching with the following special characters: . and *	Hard	-	-	go
026	Google	-	Medium	-	-	go
027	Facebook	-	Easy	-	-	go
028	Palantir	-	Medium	-	-	go
029	Amazon	-	Easy	-	-	go
030	Facebook	-	Medium	-	-	go
031	Google	Given two strings, compute the edit distance between them.	Easy	-	C++	go
032	Jane Street	-	Hard	-	-	go
033	Microsoft	-	Easy	-	-	go
034	Quora	-	Medium	-	-	go
035	Google	-	Hard	-	-	go
036	Dropbox	-	Medium	-	-	go
037	Google	The power set of a set is the set of all its subsets. Write a function that given a set, generates its power set.	Easy	-	C++	go
038	Microsoft	-	Hard	-	-	go
039	Dropbox	-	Medium	-	-	go
040	Google	-	Hard	-	-	go
041	Facebook	-	Medium	-	-	go
042	Google	-	Hard	-	-	go
043	Amazon	-	Easy	-	-	go
044	Google	-	Medium	-	-	go
045	Two Sigma	-	Easy	-	-	go
046	Amazon	-	Hard	-	-	go
047	Facebook	-	Easy	-	-	go
048	Google	-	Medium	-	-	go
049	Amazon	Given an array of numbers, find the maximum sum of any contiguous subarray of the array.	Medium	-	C++	go
050	Microsoft	-	Easy	-	-	go
051	Facebook	-	Medium	-	-	go
052	Google	-	Hard	-	-	go
053	Apple	Implement a queue using two stacks.	Medium	-	C++	go
054	Dropbox	-	Hard	-	-	go
055	Microsoft	-	Easy	-	-	go
056	Google	-	Medium	-	-	go
057	Amazon	-	Medium	-	-	go
058	Amazon	Given such an array, find the index of the element in the array in faster than linear time.	Medium	-	C++	go
059	Google	-	Hard	-	-	go
060	Facebook	-	Medium	-	-	go
061	Google	-	Medium	-	-	go
062	Facebook	-	Medium	-	-	go
063	Microsoft	-	Easy	-	-	go
064	Google	-	Hard	-	-	go
065	Amazon	Given a N by M matrix of numbers, print out the matrix in a clockwise spiral.	Easy	-	C++	go
066	Square	-	Medium	-	-	go
067	Google	-	Hard	-	-	go
068	Google	-	Medium	-	-	go
069	Facebook	Given a list of integers, return the largest product that can be made by multiplying any three integers.	Easy	-	C++	go
070	Microsoft	-	Easy	-	-	go
071	Two Sigma	-	Easy	-	-	go
072	Google	-	Hard	-	-	go
073	Google	-	Easy	-	-	go
074	Apple	Given integers N and X, write a function that returns the number of times X appears as a value in an N by N multiplication table.	Medium	-	C++	go
075	Microsoft	-	Hard	-	-	go
076	Google	-	Medium	-	-	go
077	Snapchat	-	Easy	-	-	go
078	Google	-	Medium	-	-	go
079	Facebook	-	Medium	-	-	go
080	Google	-	Easy	-	-	go
081	Yelp	-	Easy	-	-	go
082	Microsoft	-	Easy	-	-	go
083	Google	-	Medium	-	-	go
084	Amazon	-	Medium	-	-	go
085	Facebook	-	Medium	-	-	go
086	Google	-	Medium	-	-	go
087	Uber	-	Hard	-	-	go
088	ContextLogic	-	Medium	-	-	go
089	LinkedIn	-	Medium	-	-	go
090	Google	-	Medium	-	-	go
091	Dropbox	Fix the code snippet to print 0-9	Easy	-	Python	go
092	Airbnb	-	Hard	-	-	go
093	Apple	-	Hard	-	-	go
094	Google	-	Easy	-	-	go
095	Palantir	-	Hard	-	-	go
096	Microsoft	-	Easy	-	-	go
097	Stripe	-	Medium	-	-	go
098	Coursera	-	Easy	-	-	go
099	Microsoft	-	Medium	-	-	go
100	Google	-	Easy	-	-	go
101	Alibaba	-	Easy	-	-	go
102	Lyft	-	Medium	-	-	go
103	Square	-	Medium	-	-	go
104	Google	-	Easy	-	-	go
105	Facebook	-	Easy	-	-	go
106	Pinterest	-	Medium	-	-	go
107	Microsoft	-	Easy	-	-	go
108	Google	-	Easy	-	-	go
109	Cisco	-	Medium	-	-	go
110	Facebook	-	Medium	-	-	go
111	Google	-	Hard	-	-	go
112	Twitter	-	Hard	-	-	go
113	Google	-	Medium	-	-	go
114	Facebook	-	Hard	-	-	go
115	Google	-	Hard	-	-	go
116	Jane Street	-	Medium	-	-	go
117	Facebook	-	Easy	-	-	go
118	Google	-	Easy	-	-	go
119	Google	-	Medium	-	-	go
120	Microsoft	-	Medium	-	-	go
121	Google	-	Hard	-	-	go
122	Zillow	-	Medium	-	-	go
123	LinkedIn	-	Hard	-	-	go
124	Microsoft	-	Easy	-	-	go
125	Google	-	Easy	-	-	go
126	Facebook	Write a function that rotates a list by k elements.	Medium	-	C++	go
127	Microsoft	Given two linked lists in this format, return their sum in the same linked list format.	Easy	-	C++	go
128	None	-	Medium	-	-	go
129	None	-	Medium	-	-	go
130	Facebook	-	Medium	-	-	go
131	Snapchat	-	Medium	-	-	go
132	Riot Games	-	Easy	-	-	go
133	Amazon	-	Medium	-	-	go
134	Facebook	-	Easy	-	-	go
135	Apple	-	Easy	-	-	go
136	Google	-	Medium	-	-	go
137	Amazon	-	Medium	-	-	go
138	Google	-	Hard	-	-	go
139	Google	-	Medium	-	-	go
140	Facebook	-	Medium	-	-	go
141	Microsoft	-	Hard	-	-	go
142	Google	-	Hard	-	-	go
143	Amazon	-	Medium	-	-	go
144	Google	-	Medium	-	-	go
145	Google	-	Easy	-	-	go
146	BufferBox	-	Medium	-	-	go
147	None	-	Hard	-	-	go
148	Apple	-	Medium	-	-	go
149	Goldman Sachs	-	Hard	-	-	go
150	LinkedIn	-	Hard	-	-	go
151	None	-	Medium	-	-	go
152	Triplebyte	-	Medium	-	-	go
153	None	-	Hard	-	-	go
154	Amazon	-	Easy	-	-	go
155	MongoDB	-	Medium	-	-	go
156	Facebook	-	Medium	-	-	go
157	Amazon	-	Easy	-	-	go
158	Slack	-	Medium	-	-	go
159	Google	Given a string, return the first recurring character in it, or null if there is no recurring character.	Easy	-	C++	go
160	Uber	-	Hard	-	-	go
161	Facebook	-	Easy	-	-	go
162	Square	-	Medium	-	-	go
163	Jane Street	-	Hard	-	-	go
164	Google	-	Medium	-	-	go
165	Google	-	Medium	-	-	go
166	Uber	-	Medium	-	-	go
167	Airbnb	-	Hard	-	-	go
168	Facebook	-	Medium	-	-	go
169	Google	-	Medium	-	-	go
170	Facebook	-	Medium	-	-	go
171	Amazon	-	Easy	-	-	go
172	Dropbox	-	Medium	-	-	go
173	Stripe	-	Easy	-	-	go
174	Microsoft	-	Medium	-	-	go
175	Google	-	Easy	-	-	go
176	Bloomberg	-	Easy	-	-	go
177	Airbnb	-	Easy	-	-	go
178	Two Sigma	Find the expected values of 5->6 and 5->5 dice games.	Hard	-	C++	go
179	Google	-	Medium	-	-	go
180	Google	Given a stack of N elements, interleave the first half of the stack with the second half reversed using only one other queue. This should be done in-place.	Medium	-	C++	go
181	Google	-	Hard	-	-	go
182	Facebook	-	Medium	-	-	go
183	Twitch	-	Hard	-	-	go
184	Amazon	-	Easy	-	-	go
185	Google	-	Easy	-	-	go
186	Microsoft	-	Hard	-	-	go
187	Google	-	Easy	-	-	go
188	Google	-	Medium	-	-	go
189	Google	Given an array of elements, return the length of the longest subarray where all its elements are distinct.	Easy	-	C++	go
190	Facebook	Given a circular array, compute its maximum subarray sum in O(n) time. A subarray can be empty, and in this case the sum is 0.	Medium	-	C++	go
191	Stripe	-	Easy	-	-	go
192	Google	-	Medium	-	-	go
193	Affirm	-	Hard	-	-	go
194	Facebook	-	Easy	-	-	go
195	Google	-	Hard	-	-	go
196	Apple	-	Easy	-	-	go
197	Amazon	-	Easy	-	-	go
198	Google	-	Medium	-	-	go
199	Facebook	-	Hard	-	-	go
200	Microsoft	-	Hard	-	-	go
201	Google	-	Easy	-	-	go
202	Palantir	-	Easy	-	-	go
203	Uber	-	Medium	-	-	go
204	Amazon	-	Easy	-	-	go
205	IBM	-	Easy	-	-	go
206	Twitter	Given an array and a permutation, apply the permutation to the array.	Easy	-	C++	go
207	Dropbox	-	Medium	-	-	go
208	LinkedIn	-	Medium	-	-	go
209	YouTube	-	Hard	-	-	go
210	Apple	-	Easy	-	-	go
211	Microsoft	-	Medium	-	-	go
212	Dropbox	-	Easy	-	-	go
213	Snapchat	-	Medium	-	-	go
214	Stripe	Given an integer n, return the length of the longest consecutive run of 1s in its binary representation.	Easy	-	C++	go
215	Yelp	-	Medium	-	-	go
216	Facebook	-	Medium	-	-	go
217	Oracle	-	Hard	-	-	go
218	Yahoo	-	Medium	-	-	go
219	Salesforce	-	Hard	-	-	go
220	Square	-	Medium	-	-	go
221	Zillow	-	Easy	-	-	go
222	Quora	-	Medium	-	-	go
223	Palantir	-	Hard	-	-	go
224	Amazon	-	Easy	-	-	go
225	Bloomberg	-	Easy	-	-	go
226	Airbnb	-	Hard	-	-	go
227	Facebook	-	Easy	-	-	go
228	Twitter	-	Medium	-	-	go
229	Flipkart	-	Medium	-	-	go
230	Goldman Sachs	-	Medium	-	-	go
231	IBM	-	Easy	-	-	go
232	Google	-	Easy	-	-	go
233	Apple	Implement the function fib(n), which returns the nth number in the Fibonacci sequence, using only O(1) space.	Easy	-	C++	go
234	Microsoft	-	Hard	-	-	go
235	Facebook	-	Hard	-	-	go
236	Nvidia	-	Medium	-	-	go
237	Amazon	-	Easy	-	-	go
238	MIT	-	Hard	-	-	go
239	Uber	-	Medium	-	-	go
240	Spotify	-	Hard	-	-	go
241	Palantir	-	Easy	-	-	go
242	Twitter	-	Hard	-	-	go
243	Etsy	-	Medium	-	-	go
244	Square	-	Easy	-	-	go
245	Yelp	-	Medium	-	-	go
246	Dropbox	-	Medium	-	-	go
247	PayPal	-	Easy	-	-	go
248	Nvidia	-	Hard	-	-	go
249	Salesforce	-	Hard	-	-	go
250	Google	-	Medium	-	-	go
251	Amazon	-	Medium	-	-	go
252	Palantir	-	Easy	-	-	go
253	PayPal	-	Medium	-	-	go
254	Yahoo	-	Medium	-	-	go
255	Microsoft	-	Easy	-	-	go
256	Fitbit	-	Medium	-	-	go
257	WhatsApp	-	Easy	-	-	go
258	Morgan Stanley	-	Easy	-	-	go
259	Two Sigma	-	Hard	-	-	go
260	Pinterest	-	Medium	-	-	go
261	Amazon	-	Easy	-	-	go
262	Mozilla	-	Medium	-	-	go
263	Nest	-	Medium	-	-	go
264	LinkedIn	-	Hard	-	-	go
265	Atlassian	-	Easy	-	-	go
266	Pivotal	-	Easy	-	-	go
267	Oracle	-	Hard	-	-	go
268	Indeed	-	Medium	-	-	go
269	Microsoft	-	Easy	-	-	go
270	Twitter	-	Medium	-	-	go
271	Netflix	-	Hard	-	-	go
272	Spotify	-	Medium	-	-	go
273	Apple	A fixed point in an array is an element whose value is equal to its index. Given a sorted array of distinct elements, return a fixed point, if one exists. Otherwise, return False.	Easy	-	C++	go
274	Facebook	-	Hard	-	-	go
275	Epic	-	Medium	-	-	go
276	Dropbox	-	Hard	-	-	go
277	Google	-	Easy	-	-	go
278	Amazon	-	Easy	-	-	go
279	Twitter	-	Easy	-	-	go
280	Pandora	-	Easy	-	-	go
281	LinkedIn	-	Medium	-	-	go
282	Netflix	-	Easy	-	-	go
283	Google	-	Easy	-	-	go
284	Yext	-	Medium	-	-	go
285	Mailchimp	-	Medium	-	-	go
286	VMware	-	Hard	-	-	go
287	Quora	-	Medium	-	-	go
288	Salesforce	-	Medium	-	-	go
289	Google	-	Hard	-	-	go
290	Facebook	-	Easy	-	-	go
291	Glassdoor	-	Medium	-	-	go
292	Twitter	-	Hard	-	-	go
293	Uber	-	Hard	-	-	go
294	Square	-	Medium	-	-	go
295	Stitch Fix	-	Medium	-	-	go
296	Etsy	-	Hard	-	-	go
297	Amazon	-	Medium	-	-	go
298	Google	-	Easy	-	-	go
299	Samsung	-	Medium	-	-	go
300	Uber	-	Easy	-	-	go
301	Triplebyte	-	Medium	-	-	go
302	Uber	-	Medium	-	-	go
303	Microsoft	-	Easy	-	-	go
304	Two Sigma	-	Hard	-	-	go
305	Amazon	-	Easy	-	-	go
306	Palantir	-	Medium	-	-	go
307	Oracle	-	Easy	-	-	go
308	Quantcast	-	Hard	-	-	go
309	Walmart Labs	-	Medium	-	-	go
310	Pivotal	-	Easy	-	-	go
311	Sumo Logic	Given an unsorted array, in which all elements are distinct, find a "peak" element in O(log N) time.	Easy	-	C++	go
312	Wayfair	-	Easy	-	-	go
313	Citrix	-	Hard	-	-	go
314	Spotify	-	Medium	-	-	go
315	Google	-	Easy	-	-	go
316	Snapchat	-	Medium	-	-	go
317	Yahoo	-	Medium	-	-	go
318	Apple	-	Hard	-	-	go
319	Airbnb	-	Hard	-	-	go
320	Amazon	-	Medium	-	-	go
321	PagerDuty	-	Easy	-	-	go
322	Flipkart	-	Medium	-	-	go
323	Dropbox	-	Medium	-	-	go
324	Amazon	-	Easy	-	-	go
325	Jane Street	-	Easy	-	-	go
326	Netflix	-	Hard	-	-	go
327	Salesforce	-	Easy	-	-	go
328	Facebook	-	Medium	-	-	go
329	Amazon	-	Hard	-	-	go
330	Dropbox	-	Hard	-	-	go
331	LinkedIn	-	Medium	-	-	go
332	Jane Street	-	Easy	-	-	go
333	Pinterest	-	Medium	-	-	go
334	Twitter	Write a function that plays the 24 game.	Easy	-	C++	go
335	Google	-	Hard	-	-	go
336	Microsoft	-	Medium	-	-	go
337	Apple	-	Hard	-	-	go
338	Facebook	-	Medium	-	-	go
339	Microsoft	-	Easy	-	-	go
340	Google	-	Easy	-	-	go
341	Google	-	Easy	-	-	go
342	Stripe	-	Medium	-	-	go
343	Google	-	Medium	-	-	go
344	Adobe	-	Hard	-	-	go
345	Google	-	Medium	-	-	go
346	Airbnb	-	Medium	-	-	go
347	Yahoo	You are given a string of length N and a parameter k. The string can be manipulated by taking one of the first k letters and moving it to the end.	Easy	-	C++	go
348	Zillow	-	Easy	-	-	go
349	Grammarly	-	Hard	-	-	go
350	Uber	-	Medium	-	-	go
351	Quora	-	Hard	-	-	go
352	Palantir	-	Easy	-	-	go
353	Square	-	Medium	-	-	go
354	Google	-	Hard	-	-	go
355	Airbnb	-	Hard	-	-	go
356	Netflix	-	Hard	-	-	go
357	LinkedIn	-	Hard	-	-	go
358	Dropbox	-	Hard	-	-	go
359	Slack	-	Easy	-	-	go
360	Spotify	-	Medium	-	-	go
361	Facebook	-	Medium	-	-	go
362	Twitter	-	Easy	-	-	go
363	Squarespace	-	Medium	-	-	go
364	Facebook	-	Medium	-	-	go
365	Google	-	Hard	-	-	go
366	Flexport	-	Medium	-	-	go
367	Two Sigma	-	Medium	-	-	go
368	Google	-	Hard	-	-	go
369	Two Sigma	-	Medium	-	-	go
370	Postmates	-	Easy	-	-	go
371	Google	-	Hard	-	-	go
372	Amazon	Write a function that takes a natural number as input and returns the number of digits the input has. Don't use any loops.	Easy	-	C++	go
373	Facebook	-	Hard	-	-	go
374	Amazon	-	Hard	-	-	go
375	Google	-	Medium	-	-	go
376	Google	-	Easy	-	-	go
377	Microsoft	-	Hard	-	-	go
378	Coinbase	-	Medium	-	-	go
379	Microsoft	Given a string, generate all possible subsequences of the string.	Easy	-	C++	go
380	Nextdoor	-	Medium	-	-	go
381	Paypal	-	Easy	-	-	go
382	Google	-	Easy	-	-	go
383	Gusto	-	Medium	-	-	go
384	WeWork	-	Hard	-	-	go
385	Apple	-	Medium	-	-	go
386	Twitter	-	Easy	-	-	go
387	Amazon	-	Medium	-	-	go
388	Airtable	-	Medium	-	-	go
389	Google	-	Hard	-	-	go
390	Two Sigma	-	Medium	-	-	go
391	Facebook	-	Hard	-	-	go
392	Google	-	Hard	-	-	go
393	Airbnb	-	Medium	-	-	go
394	Uber	Given a binary tree and an integer k, return whether there exists a root-to-leaf path that sums up to k.	Easy	-	C++	go
395	Robinhood	-	Medium	-	-	go
396	Google	-	Hard	-	-	go
397	Microsoft	-	Medium	-	-	go
398	Amazon	-	Medium	-	-	go
399	Facebook	-	Hard	-	-	go