misc: prettier format all files

algorithms/README.md

@@ -1,5 +1,4 @@
-Algorithm Questions
-==
+# Algorithm Questions
 
 This section dives deep into practical tips for specific topics of algorithms and data structures which appear frequently in coding questions. Many algorithm questions involve techniques that can be applied to questions of similar nature. The more techniques you have in your arsenal, the higher the chances of passing the interview. They may lead you to discover corner cases you might have missed out or even lead you towards the optimal approach!
 
@@ -190,9 +189,10 @@ To find out if two circles overlap, check that the distance between the two cent
 Be familiar with the various graph representations, graph search algorithms and their time and space complexities.
 
 You can be given a list of edges and tasked to build your own graph from the edges to perform a traversal on. The common graph representations are:
-  - Adjacency matrix.
-  - Adjacency list.
-  - Hashmap of hashmaps.
+
+- Adjacency matrix.
+- Adjacency list.
+- Hashmap of hashmaps.
 
 A tree-like diagram could very well be a graph that allows for cycles and a naive recursive solution would not work. In that case you will have to handle cycles and keep a set of visited nodes when traversing.
 
@@ -298,15 +298,17 @@ For partitioning linked lists, create two separate linked lists and join them ba
 Linked lists problems share similarity with array problems, think about how you would do it for an array and try to apply it to a linked list.
 
 Two pointer approaches are also common for linked lists. For example:
-  - Getting the k<sup>th</sup> from last node - Have two pointers, where one is k nodes ahead of the other. When the node ahead reaches the end, the other node is k nodes behind.
-  - Detecting cycles - Have two pointers, where one pointer increments twice as much as the other, if the two pointers meet, means that there is a cycle.
-  - Getting the middle node - Have two pointers, where one pointer increments twice as much as the other. When the faster node reaches the end of the list, the slower node will be at the middle.
+
+- Getting the k<sup>th</sup> from last node - Have two pointers, where one is k nodes ahead of the other. When the node ahead reaches the end, the other node is k nodes behind.
+- Detecting cycles - Have two pointers, where one pointer increments twice as much as the other, if the two pointers meet, means that there is a cycle.
+- Getting the middle node - Have two pointers, where one pointer increments twice as much as the other. When the faster node reaches the end of the list, the slower node will be at the middle.
 
 Be familiar with the following routines because many linked list questions make use of one or more of these routines in the solution:
-  - Counting the number of nodes in the linked list.
-  - Reversing a linked list in-place.
-  - Finding the middle node of the linked list using fast/slow pointers.
-  - Merging two lists together.
+
+- Counting the number of nodes in the linked list.
+- Reversing a linked list in-place.
+- Finding the middle node of the linked list using fast/slow pointers.
+- Merging two lists together.
 
 #### Corner Cases
 
@@ -339,10 +341,10 @@ If the question asks to implement an operator such as power, squareroot or divis
 
 #### Some common formulas:
 
-- Sum of 1 to N = (n+1) * n/2
+- Sum of 1 to N = (n+1) \* n/2
 - Sum of GP = 2<sup>0</sup> + 2<sup>1</sup> + 2<sup>2</sup> + 2<sup>3</sup> + ... 2<sup>n</sup> = 2<sup>n+1</sup> - 1
 - Permutations of N = N! / (N-K)!
-- Combinations of N = N! / (K! * (N-K)!)
+- Combinations of N = N! / (K! \* (N-K)!)
 
 #### Practice Questions
 
@@ -449,7 +451,7 @@ To determine if two strings are anagrams, there are a few plausible approaches:
 
 ### Palindrome
 
-A palindrome is a word, phrase, number, or other sequence of characters which reads the same backward as forward, such as *madam* or *racecar*.
+A palindrome is a word, phrase, number, or other sequence of characters which reads the same backward as forward, such as _madam_ or _racecar_.
 
 Here are ways to determine if a string is a palindrome:
 
@@ -498,7 +500,6 @@ If the question involves summation of nodes along the way, be sure to check whet
 
 You should be very familiar with writing pre-order, in-order, and post-order traversal recursively. As an extension, challenge yourself by writing them iteratively. Sometimes interviewers ask candidates for the iterative approach, especially if the candidate finishes writing the recursive approach too quickly.
 
-
 #### Corner Cases
 
 - Empty tree.
@@ -561,9 +562,9 @@ Be familiar with implementing, from scratch, a `Trie` class and its `add`, `remo
 
 #### Notes
 
-If you see a top or lowest *k* being mentioned in the question, it is usually a signal that a heap can be used to solve the problem, such as in [Top K Frequent Elements](https://leetcode.com/problems/top-k-frequent-elements/).
+If you see a top or lowest _k_ being mentioned in the question, it is usually a signal that a heap can be used to solve the problem, such as in [Top K Frequent Elements](https://leetcode.com/problems/top-k-frequent-elements/).
 
-If you require the top *k* elements use a Min Heap of size *k*. Iterate through each element, pushing it into the heap. Whenever the heap size exceeds *k*, remove the minimum element, that will guarantee that you have the *k* largest elements.
+If you require the top _k_ elements use a Min Heap of size _k_. Iterate through each element, pushing it into the heap. Whenever the heap size exceeds _k_, remove the minimum element, that will guarantee that you have the _k_ largest elements.
 
 #### Practice Questions
 

algorithms/array.md

@@ -1,26 +1,28 @@
-Arrays
-==
+# Arrays
 
 #### Hard
+
 - Given a set of rectangles represented by a height and an interval along the y-axis, determine the size of its union. ([Solution](https://www.geeksforgeeks.org/divide-and-conquer-set-7-the-skyline-problem/))
 - Given an array, find the longest arithmetic progression. ([Solution](https://www.geeksforgeeks.org/longest-arithmetic-progression-dp-35/))
-- Given an unsorted array of integers, find the length of the longest consecutive elements sequence. 
+- Given an unsorted array of integers, find the length of the longest consecutive elements sequence.
   - E.g. `[100, 4, 200, 1, 3, 2] => 4`. Explanation: The longest consecutive elements sequence is `[1, 2, 3, 4]`. Therefore its length is 4. Note: Your algorithm should run in O(n) complexity. ([Solution](https://www.geeksforgeeks.org/longest-consecutive-subsequence/))
 
 #### Medium
+
 - Given a list of item prices, find all possible combinations of items that sum a particular value `K`. ([Solution](https://www.geeksforgeeks.org/combinational-sum/))
 - Given an array of integers find whether there is a sub-sequence that sums to 0 and return it. ([Solution](https://www.geeksforgeeks.org/find-if-there-is-a-subarray-with-0-sum/))
   - E.g. `[1, 2, -3, 1]` => `[1, 2, -3]` or `[2, -3, 1]`
 - Trapping rain water: You have an array with the heights of an island (at point 1, point 2 etc) and you want to know how much water would remain on this island (without flowing away). ([Solution](https://www.geeksforgeeks.org/trapping-rain-water/))
 
 #### Easy
+
 - Implement a circular buffer using an array. ([Solution](https://www.geeksforgeeks.org/circular-queue-set-1-introduction-array-implementation/))
 - Given an array of integers, print out a histogram using the said array; include a base layer (all stars) ([Solution](https://www.geeksforgeeks.org/program-make-histogram-array/))
 - Given an array and an index, find the product of the elements of the array except the element at that index. ([Solution](https://www.geeksforgeeks.org/a-product-array-puzzle/))
 - Given 2 separate arrays, write a method to find the values that exist in both arrays and return them. ([Solution](https://www.geeksforgeeks.org/union-and-intersection-of-two-sorted-arrays-2/))
 - Given an input array and another array that describes a new index for each element, mutate the input array so that each element ends up in their new index ([Solution](https://www.geeksforgeeks.org/reorder-a-array-according-to-given-indexes/))
   - Discuss the runtime of the algorithm and how you can be sure there would not be any infinite loops
-- Given an array of non-negative numbers, find continuous subarray with sum to S.  ([Solution 1](https://www.geeksforgeeks.org/find-subarray-with-given-sum/)) ([Solution 2](http://blog.gainlo.co/index.php/2016/06/01/subarray-with-given-sum/))
+- Given an array of non-negative numbers, find continuous subarray with sum to S. ([Solution 1](https://www.geeksforgeeks.org/find-subarray-with-given-sum/)) ([Solution 2](http://blog.gainlo.co/index.php/2016/06/01/subarray-with-given-sum/))
 - Given an array of numbers list out all triplets that sum to 0. Do so with a running time of less than O(n^3). ([Solution 1](https://www.geeksforgeeks.org/find-triplets-array-whose-sum-equal-zero/)) ([Solution 2](http://blog.gainlo.co/index.php/2016/07/19/3sum/))
 - Given an array of numbers list out all quadruplets that sum to 0. Do so with a running time of less than O(n^4). ([Solution](https://www.geeksforgeeks.org/find-four-numbers-with-sum-equal-to-given-sum/))
 - Given an array of integers, find the subarray with the largest sum. ([Solution](https://www.geeksforgeeks.org/largest-sum-contiguous-subarray/))
@@ -42,6 +44,7 @@ Arrays
   - E.g., `[2, 5, 3, 2, 1, 3, 4, 5, 1]` returns 4, because it is the only value that appears in the array only once.
 
 #### Other
+
 - In an array of arrays, e.g. given `[[], [1, 2, 3], [4, 5], [], [], [6, 7], [8], [9, 10], [], []]`, print: `1, 2, 3, 4, 5, 6, 7, 8, 9, 10`.
   - Implement an iterator that supports `hasNext()`, `next()` and `remove()` methods.
 - Paginate an array with constraints, such as skipping certain items.

algorithms/bit-manipulation.md

@@ -1,5 +1,4 @@
-Bit Manipulation
-==
+# Bit Manipulation
 
 - How do you verify if an interger is a power of 2?
 - Write a program to print the binary representation of an integer.

algorithms/dynamic-programming.md

@@ -1,14 +1,15 @@
-Dynamic Programming
-==
+# Dynamic Programming
 
 - Given a flight itinerary consisting of starting city, destination city, and ticket price (2D list) - find the optimal price flight path to get from start to destination. (A variation of Dynamic Programming Shortest Path)
 - Given some coin denominations and a target value `M`, return the coins combination with the minimum number of coins.
   - Time complexity: `O(MN)`, where N is the number of distinct type of coins.
   - Space complexity: `O(M)`.
 - Given a set of numbers in an array which represent a number of consecutive days of Airbnb reservation requested, as a host, pick the sequence which maximizes the number of days of occupancy, at the same time, leaving at least a 1-day gap in-between bookings for cleaning.
+
   - The problem reduces to finding the maximum sum of non-consecutive array elements.
   - E.g.
-    ~~~
+
+    ```
     // [5, 1, 1, 5] => 10
     The above array would represent an example booking period as follows -
     // Dec 1 - 5
@@ -22,6 +23,7 @@ Dynamic Programming
     Similarly,
     // [3, 6, 4] => 7
     // [4, 10, 3, 1, 5] => 15
-    ~~~
-- Given a list of denominations (e.g., `[1, 2, 5]` means you have coins worth $1, $2, and $5) and a target number `k`, find all possible combinations, if any, of coins in the given denominations that add up to `k`. You can use coins of the same denomination more than once.
+    ```
+
+- Given a list of denominations (e.g., `[1, 2, 5]` means you have coins worth $1, $2, and \$5) and a target number `k`, find all possible combinations, if any, of coins in the given denominations that add up to `k`. You can use coins of the same denomination more than once.
 - You are climbing a flight of stairs. It takes n steps to reach to the top. Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top? E.g. Input: 3, Output: 3. Explanation: `[1, 1, 1], [1, 2], [2, 1]`.

algorithms/geometry.md

@@ -1,5 +1,4 @@
-Geometry
-==
+# Geometry
 
 - You have a plane with lots of rectangles on it, find out how many of them intersect.
 - Which data structure would you use to query the k-nearest points of a set on a 2D plane?

algorithms/graph.md

@@ -1,5 +1,4 @@
-Graph
-==
+# Graph
 
 - Given a list of sorted words from an alien dictionary, find the order of the alphabet.
   - Alien Dictionary Topological Sort question.

algorithms/hash-table.md

@@ -1,5 +1,4 @@
-Hash Table
-==
+# Hash Table
 
 - Describe an implementation of a least-used cache, and big-O notation of it.
 - A question involving an API's integration with hash map where the buckets of hash map are made up of linked lists.

algorithms/heap.md

@@ -1,5 +1,4 @@
-Heap
-==
+# Heap
 
 - Merge `K` sorted lists together into a single list.
 - Given a stream of integers, write an efficient function that returns the median value of the integers.

algorithms/interval.md

@@ -1,7 +1,7 @@
-Interval
-==
+# Interval
 
 - Given a list of schedules, provide a list of times that are available for a meeting.
+
   ```
   [
     [[4,5], [6,10], [12,14]],
@@ -12,6 +12,7 @@ Interval
   Example Output:
   [[0,4], [11,12], [16,23]]
   ```
+
 - You have a number of meetings (with their start and end times). You need to schedule them using the minimum number of rooms. Return the list of meetings in every room.
 - Interval ranges:
   - Given 2 interval ranges, create a function to tell me if these ranges intersect. Both start and end are inclusive: `[start, end]`
@@ -21,7 +22,7 @@ Interval
     - E.g. `[1, 4]` and `[3, 6]` => `[1, 6]`
   - Now create a function that takes a group of unsorted, unorganized intervals, merge any intervals that intersect and sort them. The result should be a group of sorted, non-intersecting intervals.
   - Now create a function to merge a new interval into a group of sorted, non-intersecting intervals. After the merge, all intervals should remain
-  non-intersecting.
+    non-intersecting.
 - Given a list of meeting times, check if any of them overlap. The follow-up question is to return the minimum number of rooms required to accommodate all the meetings.
   - [Source](http://blog.gainlo.co/index.php/2016/07/12/meeting-room-scheduling-problem/)
 - If you have a list of intervals, how would you merge them?

algorithms/linked-list.md

@@ -1,5 +1,4 @@
-Linked List
-==
+# Linked List
 
 - Given a linked list, in addition to the next pointer, each node has a child pointer that can point to a separate list. With the head node, flatten the list to a single-level linked list.
   - [Source](http://blog.gainlo.co/index.php/2016/06/12/flatten-a-linked-list/)

algorithms/math.md

@@ -1,5 +1,4 @@
-Math
-==
+# Math
 
 - Create a square root function.
 - Given a string such as "123" or "67", write a function to output the number represented by the string without using casting.

algorithms/matrix.md

@@ -1,5 +1,4 @@
-Matrix
-==
+# Matrix
 
 - You're given a 3 x 3 board of a tile puzzle, with 8 tiles numbered 1 to 8, and an empty spot. You can move any tile adjacent to the empty spot, to the empty spot, creating an empty spot where the tile originally was. The goal is to find a series of moves that will solve the board, i.e. get `[[1, 2, 3], [4, 5, 6], [7, 8, - ]]` where - is the empty tile.
 - Boggle implementation. Given a dictionary, and a matrix of letters, find all the words in the matrix that are in the dictionary. You can go across, down or diagonally.

algorithms/oop.md

@@ -1,5 +1,4 @@
-Object-Oriented Programming
-==
+# Object-Oriented Programming
 
 - How would you design a chess game? What classes and objects would you use? What methods would they have?
 - How would you design the data structures for a book keeping system for a library?

algorithms/permutation.md

@@ -1,5 +1,4 @@
-Permutation
-==
+# Permutation
 
 - You are given a 7 digit phone number, and you should find all possible letter combinations based on the digit-to-letter mapping on numeric pad and return only the ones that have valid match against a given dictionary of words.
 - Give all possible letter combinations from a phone number.
@@ -9,4 +8,4 @@ Permutation
   - E.g. when `N` is `3`, we should get `((()))`, `(()())`, `(())()`, `()(())`, `()()()`.
   - [Source](http://blog.gainlo.co/index.php/2016/12/23/uber-interview-questions-permutations-parentheses/)
 - Given a list of arrays, return a list of arrays, where each array is a combination of one element in each given array.
-   - E.g. If the input is `[[1, 2, 3], [4], [5, 6]]`, the output should be `[[1, 4, 5], [1, 4, 6], [2, 4, 5], [2, 4, 6], [3, 4, 5], [3, 4, 6]]`.
+  - E.g. If the input is `[[1, 2, 3], [4], [5, 6]]`, the output should be `[[1, 4, 5], [1, 4, 6], [2, 4, 5], [2, 4, 6], [3, 4, 5], [3, 4, 6]]`.

algorithms/queue.md

@@ -1,5 +1,4 @@
-Queue
-==
+# Queue
 
 - Implement a Queue class from scratch with an existing bug, the bug is that it cannot take more than 5 elements.
 - Implement a Queue using two stacks. You may only use the standard `push()`, `pop()`, and `peek()` operations traditionally available to stacks. You do not need to implement the stack yourself (i.e. an array can be used to simulate a stack).

algorithms/sorting-searching.md

@@ -1,5 +1,4 @@
-Sorting and Searching
-==
+# Sorting and Searching
 
 - Sorting search results on a page given a certain set of criteria.
 - Sort a list of numbers in which each number is at a distance `K` from its actual position.

algorithms/stack.md

@@ -1,5 +1,4 @@
-Stack
-==
+# Stack
 
 - Implementation of an interpreter for a small language that does multiplication/addition/etc.
 - Design a `MinStack` data structure that supports a `min()` operation that returns the minimum value in the stack in O(1) time.

algorithms/string.md

@@ -1,5 +1,4 @@
-String
-==
+# String
 
 - Output list of strings representing a page of hostings given a list of CSV strings.
 - Given a list of words, find the word pairs that when concatenated form a palindrome.
@@ -42,7 +41,7 @@ String
   - E.g. `1122344`, next: `21221324`, next: `12112211121214`.
   - Count and say problem.
 - Compress a string by grouping consecutive similar questions together:
-  - E.g. `'aaabbbcc' => `'a3b3c2'`.
+  - E.g. `'aaabbbcc' =>`'a3b3c2'`.
 - You have a string consisting of open and closed parentheses, but parentheses may be imbalanced. Make the parentheses balanced and return the new string.
 - Given a set of strings, return the smallest subset that contains prefixes for every string.
   - E.g. `['foo', 'foog', 'food', 'asdf']` => `['foo', 'asdf']`.

algorithms/topics.md

@@ -1,5 +1,4 @@
-Topics
-==
+# Topics
 
 ## Arrays
 

algorithms/tree.md

@@ -1,5 +1,4 @@
-Tree
-==
+# Tree
 
 - Find the height of a tree.
 - Find the longest path from the root to leaf in a tree.