## Algorithm Interview Questions

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For a given amount of currency, find the minimum set of bills. The currency set is the following: 0.01, 0.05, 0.1, 0.25, 1, 5, 10, 20, 50, and 100. For example, for 21.28, 1 20 bill, and 1 1 bill, and 1 0.25 bill and 3 0.01 bills.

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What is the best way to generate first N primes? (not primes up to N but first N primes)

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**Game of Bits**

Yale and Xavier are playing a game with numbers. Each round of the game starts with a number given to them by Zita, Yale’s little sister.

The number n is expressed as a binary integer with p bits

For every round, Xavier gets the first move.

The game came consists of moves performed by Yale and Xavier alternately.

The mth move of the game involves performing these operations on the number:

Toggling the mth bit (numbering of bits starts from left) of the number.

Toggling the left adjacent bit of m (if such a bit exists) if it is equal to the mth bit before toggling in step 1; otherwise keep it as is.

Toggling the right adjacent bit of m (if such a bit exists) if it is equal to the mth bit before toggling in step 1; otherwise keep it as is.

This modification of the number goes on until all p moves are made. If the modified number (as a result of all the operations) is

equal (or a distance one away) from the original number, then the person who made the last move wins the round; otherwise the other one wins the round.

**Note:**

The number given to them is converted to its binary form and represented with the help of minimum number of bits.

The numbering for the bits starts from the leftmost bit.

**Constraints**

1<=r<=10^6

1<=n<=10^6, where n is the number given by Zita in any round

**Input Format**

The first line contains a number, r, denoting the number of rounds in the game.

This is followed by r lines, where the ith line contains the number given by Zita for the ith round.

**Output Format**

The output of the problem has r lines, where the ith line contains the winner of ith round as X if Xavier wins ith round or Y if Yale wins the ith round.

**Sample Input**

1

11

**Sample Output**

Y

**Explanation**

11 is represented as 1011 using minimum number of bits in binary.

When Xavier makes the first move, it becomes 0011.

Then Yale makes the 2nd move and it becomes 1111.

After the third move made by Xavier, it becomes 1000.

After the last move by Yale, it becomes 1011 which is 11 in decimal.

The last move was made Yale and the modified number is equal or adjacent to 11,

therefore, Yale wins this round.

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You have been given a string and a number. You need to find the longest common suffix between string and substring(0 to number)

Example : String = "ababa"

Number is 3

Take a substring from 0 to 2 which is aba

now find the longest matching suffix between "ababa" and "aba"

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I don't remember perfectly the question, but it was like this

Given a list of 100 songs on your cell phone, find a way for each user to hear the songs without repeating songs, you need to use an algorithm that uses shuffle for songs.

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Given 2 strings representing very large numbers (these are not representable as a BigInteger or other various type) write a method for adding the two numbers and returning their sum.

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Design and implement a interest matching algo, to match people according to their interests in a particular area.

Suggest a score based on their interests. And rank matchings accordingly.

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In a Binary maze with 0 and 1, 0 is the valid cell to which we can travel and 1 means that the cell is blocked. Given source and destination. We have to find-

1. IF path exists, if yes, find shortest path.

2. If we are given a chance to toggle single cell from 1 to 0 , which cell you will toggle so that you will surely get the shortest path.

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set of locations on the map. Example, 4 places in zone 1. 2 places in zone2, 1 place in zone3 and 2 in zone4. 2 aircraft are assigned, A1, A2. A1 can fly faster. A2 is slower but farther than A1. Each day A1 can visit one location in any zone whereas A2 can visit 2 locations in any zone. what is the optimized number of visits by A1 and A2 at the end of 30 days.

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Given a map represented as a 2d array with only 0’s and 1’s. An island is a group of connected 1’s. Find out how many distinct islands(can be rotated).

eg:

1 1 0 0

1 0 0 0

0 0 0 1

0 0 1 1

return 2.

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Given a wall, which is made up of two types of bricks (Porus / opaque ). Porus bricks allow water pass through them. Opaque won't. Find whether water reaches to ground, if there is any rainfall.

Water can flow from top to bottom, diagonally, horizontally as well. Only flowing from bottom to top is not possible.

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Given an infinitely large array and every element has tags associated with them, and there are about 10,000 tags (say) then sort the given array to get all tag-0’s first, tag-1’s next and so on in O(n).

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water capacity in a histogram

what is the capacity if an array value becomes 0 - which will make the water to flow off the histogram

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Reverse a linked list

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Find Duplicate number from a huge amount of data which cannot fit in the memory.

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Find kth-largest number from a huge amount of data which cannot fit in the memory.

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Given a random MxN matrix and a positive integer, recursively Your program should then find a continuous path thought the matrix starting at position 0,0 that will sum to n. Your program shouldomly move left (col -1), right(col +1), up (row -1) and down (row+1)and can only use a position once in the sum. if there is a such path in the matrix, create the path in a separate matrix with the same size, and replacing the indices used with 1 and the rest 0.

- 2of 2 votes
Yahoo Sunnyvale onsite

A string s3 consists of multiple repetitions of s1.

Given s1 and another string s2, find if s2 is a substring of s3.

s3 = s1 + s1 + … + s1 = n * s1, where n is a positive integer 0.

For example

s1 = “aabc”, s2 = “caa” => true

s1 = “aabc”, s2 = “cab” => false

s1 = “aabc”, s2 = “caabcaa” => true

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A city represented by a rectangular matrix is divided into plot of lands, and the cost of each plot is known. Find the largest rectangular area of land we can buy, within a budget B.

4 6 7

3 5 2

2 4 5

B = 16

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Amazon phone interview

A queue of people are waiting to buy ice cream from you.

Each person buys one ice cream, which sells for $5.

Each customer is holding a bill of $5, $10 or $20.

Your initial balance is 0.

Find whether you will be able to make change for every customer in the queue. You must serve customers in the order they come in.

For example

5, 5, 5, 10, 20 -> true,

5, 5, 10 -> true,

10, 10 -> false

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Congrats on aonecode member A.P. for signing the offer with FB! Thanks for sharing the experience with us.

phone:

postorder tree traversal recursive -> iterative

add two binary number

on-site:

1 ring buffer

2 merge intervals

3 Leetcode alien dictionary

4.sort list of words

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Airbnb: Design webbrowser back button

Your web browser supports will support three actions: back, forward and open. The init webpage is “about:blank”.

Given a sequence of commands. Return the result page.

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You have been given a generator string ab from which any number of strings can be generated recursively by inserting ‘ab’ at any location. You have been given an input string to check if that given string is valid or not.(i.e. generated by given with given string.)

eg.

Input: aabbab

Output: valid

Input: abbaab

Output: Invalid

I could not come up with a algorithm less than O(N*N)

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Search for a sorted integer in an integer array that has been rotated multiple times.

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Print the bottom view of a Binary Tree.

ex-`1 2 3 4 5 7 8 9 10`

result is 4, 8, 5, 9, 7, 10

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Given an alphabet where we do not know the order of the letters also do not know the number of letters.

We are give an input list of tuples where each entry in the list gives an ordering between the 2 letters

Determine the alphabet order.

Ex-

<A, B>

<C, D>

<C, E>

<D, E>

<A, C>

<B, C>

Order is A, B, C, D, E

- 2of 2 votes
AWS phone interview

Find the left view of binary tree

1

/ \

2 3

/\ \

4 5 6

/ /

7 8

/

9

return [1, 2, 4, 7, 9]

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April Google Interview 1/4

A = a+b-c-a-b-c-a-b (Tree)

B = b+a+c+a+b-c+b (Tree)

is A equal to B

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April Google Interview 4/4

Build HTML Reverser

Given

<A>(hello)(<P>ab</P>)(<S>hi</S>)</A>

Return

<A>(<S>ih</S>)(<P>ba</P>)(olleh)</A>