CareerCup

Solve the 24 Game

Problem:
Given 100 stones, two players alternate to take stones out. One can take any number from 1 to 15; however, one cannot take any number that was already taken. If in the end of the game, there is k stones left, but 1 - k have all been previously taken, one can take k stones. The one who takes the last stone wins. How can the first player always win?

My Idea
Use recursion (or dynamic programming). Base case 1, where player 1 has a winning strategy.
Reducing: for n stones left, if palyer 1 takes m1 stones, he has to ensure that for all options player 2 has (m2), he has a winning strategy. Thus the problem is reduced to (n - m1 - m2).

Follow Up Question:
If one uses DP, the potential number of tables to be filled is large (2^15), since the available options left depend on the history, which has 2^15 possibilities.
How can you optimize?

I don't have a great answer to the follow up question。。。

Round4
Starting from num = 0, add 2^i (where i can be any non-negative integer) to num until num == N. Print all paths of how num turns from 0 to N.
For example if N = 4,
Paths printed are [0,1,2,3,4], [0,1,2,4], [0,1,3,4], [0,2,4], [0,2,3,4], [0,4].
[0,2,4] is made from 0 + 2^1 + 2^1. [0,1,3,4] from 0 + 2^0 + 2^1 + 2^0

Round3
For N light bulbs, implement two methods
I. isOn(int i) - find if the ith bulb is on or off.
II. toggle(int start, int end)

Round1
Find if two people in a family tree are blood-related.

Round2
Given some nodes in a singly linked list, how many groups of consecutively connected nodes there is.
For linked list
0->1->2->3->4->5->6,
given nodes 1, 3, 5, 6
there are 3 groups [1], [3], and [5, 6].

Explain the linear piecewise function.

Explain event driven programming in C with example

We have N gas stations, and we are given all the distances between each pair of station. So we have nC2 distances provided to us. For example if I have 3 stations namely A, B, C the distances provided will be AB, AC, BC. We have to find the exact position of each gas station provided with these nC2 distances.

eg. we have 5 stations so 5C2 distances are given in random order - 10, 20, 70, 80, 30, 20, 100, 70, 50, 90

Output the exact positions of gas stations A, B, C, D, E
i.e
A - 0
B - 10
C - 30
D - 80
E - 100

refer this image for more clarity

https://drive.google.com/open?id=0BxPkptdH01OBZzEwX29iRGI4cEU

Round 5:
Given a set of synonyms such as (fast, quick), (fast, speedy), (learn, study), decides if two sentences were synonymous.
(The sentences were structurally the same and has the same number of words in them.
The synonymous relation [fast ~ quick] and [fast ~ speedy] does not necessarily mean [quick ~ speedy].)

Follow-up:
If the synonymous relation passes down so that [fast ~ quick] and [fast ~ speedy] implies [quick ~ speedy], decide if two sentences were synonymous.

Round 4:
Implement a class Employment with these 3 methods: assignManager(p1, p2): assign p1 as p2's manager. beColleague(p1, p2): make p1 and p2 peer colleagues. isManager((p1, p2): decide if p1 is the manager of p2.

Round 3
Given a matrix of 0s and 1s where 0 is wall and 1 is pathway, print the shortest path from the first row to the last row.
Can walk to the left, top, right, bottom at any given spot.

Follow-up:
If every pathway takes a cost (positive integer) to get through, print the minimum cost path from the first row to the last row.

Google on-site June
Round 1
Leetcode 10

Round 2
Select a random point uniformly within a rectangle, (The side of rectangle is parallel to the x/ y grid).

Follow-up: Given multiple non-overlapped rectangles on the 2D grid, uniformly select a random point from the rectangles.

Phone Interview Amazon, Seattle
I. Get the sum of all prime numbers up to N. primeSum(N).
Follow-up: If primeSum(N) is frequently called, how to optimize it.

II. OODesign Parking Lot

Given a list of input tasks to run, and the cooldown interval, output the minimum number of time slots required to run them.
// Tasks: 1, 1, 2, 1, 2
// Recovery interval (cooldown): 2
// Output: 8 (order is 1 _ _ 1 2 _ 1 2 )

=========
Tasks are task numbers in that order coming in for execution. Cooling time is time interval required to cool down the machine after executing a task. So it's like if CPU executed task 1 then it needs 2 cooling time intervals before executing another task 1 but meanwhile, it can execute other tasks which are not same as 1 and so on. So before executing any task, you have to check if you have executed same task number before and if yes, then if its cooling time interval is done or not.
The output is basically the number of cycles/time slots CPU took to execute these tasks in that order (including when task executed and cooling intervals).

Apple Map Team
1. Given an array A and some queries, query(i, j) returns the result of Ai*...*Aj, in other words the multiplication from Ai to Aj.
The numbers in A are non-negative.
Implement query(i, j).

2. Flatten nested linked list

3. POI search design

4. LC238 & LC279

You are given an old touch smartphone numbers having dial pad and calculator app.


Aim: The goal is to type a number on dialpad.

But as phone is old, some of the numbers and some operations can't be touched.
For eg. 2,3,5,9 keys are not responding , i.e you cannot use them
But you can always make a number using other numbers and operations in Calculator. There could be multiple ways of making a number

.Calculator have 1-9 and +,-,*,/,= as operations. Once you have made the number in Calculator you can copy the number and use it.

You have to find minimum number to touches required to obtain a number.


#Input:#
There will be multiple Test cases .Each test case will consist of 4 lines
1) First line will consist of N,M,O
N: no of keys working in Dialpad (out of 0,1,2,3,4,5,6,7,8,9)
M:types of operations supported (+,-,*,/)
O: Max no of touches allowed

2) second line of input contains the digits that are working e.g 0,2,3,4,6.
3) Third line contains the valued describing operations, 1(+),2(-),3(*),4(/)

4) fourth line contains the number that we want to make .

#Output:#
Output contains 1 line printing the number of touches required to make the number


#Sample Test Case:#
1 // No of test cases
5 3 5 // N ,M, O
1 2 4 6 0 // digits that are working (total number of digits = N),
1 2 3 // describing operations allowed (1--> '+', 2--> '-', 3--> '*' , 4--> '/' )(total number is equals to M)
5 // number we want to make


Answer 3
How 4? 1+4= , "=" is also counted as a touch



2nd Sample Case
3 // No of Test cases
6 4 5 // N ,M, O
1 2 4 6 9 8 // digits that are working (total number of digits = N),
1 2 3 4 // describing operations allowed (1--> +, 2--> -, 3--> , 4-->/)
91 // number we want to make
6 2 4 // 2nd test case
0 1 3 5 7 9
1 2 4 // +, -, / allowed here
28
5 2 10
1 2 6 7 8
2 3 // -, allowed
981

#Output:#
2 // 91 can be made by directly entering 91 as 1,9 digits are working, so only 2 operations
5// 35-7=, other ways are 1+3*7=
9//62*16-11=


Order for computation will be followed as symbols entered, if + comes, it will be computed first


One more example: lets say 1,4,6,7,8,9 works and +,-,* works.
2,3,5 and / doesn't work.
If you have to type 18-> 2 operations. (Each touch is considered an operation),br> If you have to type 5 -> '1+4=' that requires 4 operations. There could be other ways to make '5'.

Complete the puzzle which simulates generic directory structures.
* The solution should be directory agnostic.
* Be succinct yet readable. You should not exceed more than 200 lines.
* Consider adding comments and asserts to help the understading.
* Code can be compiled with javac Directory.java
* Code should be executed as: java -ea Directory (-ea option it's to enabled the assert)
*/


/**
* change the code here.
*/
class Shell {

Shell cd(final String path) {
return this;
}

public String path() {
return "/";
}
}

public class Directory {

public static void main(String[] args) {

final Shell shell = new Shell();
assert shell.path().equals("/");

shell.cd("/");
assert shell.path().equals("/");

shell.cd("usr/..");
assert shell.path().equals("/");

shell.cd("usr").cd("local");
shell.cd("../local").cd("./");
assert shell.path().equals("/usr/local");

shell.cd("..");
assert shell.path().equals("/usr");

shell.cd("//lib///");
assert shell.path().equals("/lib");
}
}

4/5 Round at Uber
Coding: Given a 2D array of either '\' or '/', find out how many pieces this rectangle is divided into graphically.
For a 2X2 matrix with
/\
\/
The matrix split into 5 pieces - the diamond in middle and the four corners. Return 5 as the answer.


5/5 Round at Uber
Design Excel.

2/5 Round at Uber
Bar raiser - Behavioral questions. Coding: Find if a set of meetings overlap. Meeting has a starttime and an endtime with accuracy to minute. All meetings take place in the same day. Do this in O(n) time.

3/5 Round at Uber
Coding: Subset sum. Follow-up: Optimize the solution.

1/5 Round at Uber
Manager : Behavioral questions. Basic system design concepts. Publish/subscribe model. Discussion on Uber architecture.

I've got these trees of integers; they're like regular trees, but they can share nodes.
I need to know if any branch of this tree sums to 100.
7
/ \
8 6
/ \ / \
2 3 9
/ \ / \ / \
5 4 1 100

Follow up question was how would you change the code to handle negative numbers.

Uber
1. Mirror Binary Tree
2. String pattern matching
The matching should cover the entire input string (not partial).
The function prototype should be:
bool isMatch(String str, String pattern)
Some examples:
isMatch("aa","a") → false
isMatch("aa","aa") → true
isMatch("aaa","aa") → false
isMatch("aa","a{1,3}") → true
isMatch("aaa","a{1,3}") → false
isMatch("ab","a{1,3}b{1,3}") → true
isMatch("abc","a{1,3}b{1,3}c") → true
isMatch("abbc","a{1,3}b{1,2}c") → false
isMatch("acbac","a{1,3}b{1,3}c") → false
isMatch("abcc","a{1,3}b{1,3}cc{1,3}") → true
In pattern string, a char followed by {lower, upper} means that the char occur lower to upper(exclusive) times. e.g. a{1, 3} -> a occurs 1 or 2 times.

given a list of numbers, put with + - * / any two number, find the maximum value you can get.
int getMaxNumber(int[] nums){
}

3.1 design: design fb inbox search —> just focus on the post

4.1 binary tree to circular double linked list.
4.2 two arrays, find the common elements of two sorted array. if one array is small, the other is very big.

2.1 career discussion
2.2 divide two numbers with no / or %

1/4 round of FB on-site interview, Master Degree, Hired
1.1 diameter of tree
1.2 find the point which have the maximum overlap of intervals

1 year exp. Interviewed at Cambridge, MA

Round1
LC304. Follow-up: given a char stream instead a string as the input, get the longest substring with at most K distinct characters.

Round2
Find out the area of a number of squares on a plane, an advanced version of LC223.
Had no clue on that problem at all so the interviewer kindly gave another one LC305.

Round3
Similar to LC393 but the interviewer made a slightly different rule for encoding.
Follow-up: decode with utf-16. It took quite a while for me to understand the rules.

Round4
Card game rule: the hand is drawn from a pack of cards (no jokers).
Play cards ONLY when they are
1. 3 of a kind ('AAA' ) or 4 of a kind('AAAA’).
2. a straight flush of 3 or more cards('JQK' or 'A23456...' in the same suit).
Find out whether the player is able to play the whole hand given.
e.g. [Spade A, Spade K, Spade Q, Diamond Q, Heart Q] return false.
[Spade A, Spade K, Spade Q, Diamond Q, Heart Q, Club Q] return true.

given a string of number, you can add a + or * sign between any two numbers, find the maximum value you can get
ex. s = "89" --> 8 * 9 = 72
int maxNumber(String s){}

A new species has been discovered and we are trying to understand their form of communication. So, we start by identifying their alphabet. Tough Mr. Brown managed to steal a vocabulary that has words in it in ascending order and a team already identified the letters. So, we have now ordered words as sequences of numbers, print every letter once in ascending order.

[3,2]
[4,3,2]
[4,1,1]
[1, 2]
[1, 1]

alphabet: [3, 4, 2, 1]