IOT Challenge: Build IOT Device and Win Prizes – FREE Azure Sphere Kit

Hackster is hosting an IOT challenge: “Secure Everything with Azure Sphere”, build your IOT device and win prizes.

Head to: https://www.hackster.io/contests/SecureEverything

At the least, you can get free Azure Sphere Kit, worth $75 !!


Fair Distribution Algorithm

Given 5 boxes with different weight [24, 27, 17, 15, 17], distribute the weight as even as possible among 3 trucks of the same size. The trucks can fit unlimited number of boxes. The weight of the boxes can’t be transferred, for example move 4 from box 1 (originally weight 24) and transfer to box 2.

What if we have more boxes with different weight, let’s say 6 boxes with weight of [1, 2, 17, 21, 7, 6].

What if the number of truck change to 5 trucks?

What’s the most effective algorithm to distribute the boxes evenly (in weight) within all the trucks?

Left-Shift Operator Is Limited?

Why is left-shift operator with 32 result in lower number?

int i = 1;
(i << 0).Dump(); // Result is 1
(i << 1).Dump(); // Result is 2
(i << 2).Dump(); // Result is 3
(i << 3).Dump(); // Result is 8
(i << 10).Dump(); // Result is 1024
(i << 20).Dump(); // Result is 1048576
(i << 30).Dump(); // Result is 1073741824
(i << 31).Dump(); // Result is -2147483648
(i << 32).Dump(); // Result is 1 -> WHY?

Algorithm for Shortest Path

Today’s tech challenge comes from Garry Trinder’s The Old New Thing.

Consider a two-dimensional board, tall and narrow. Into the board are nailed a number of horizontal obstacles. Place a water faucet at the top of the board and turn it on. The water will dribble down, and when it hits an obstacle, some of the water will go left and some will go right. The goal is to find the shortest path to the ground from a given starting position, counting both horizontal and vertical distance traveled.

The illustration:

algorithm-for-shortest-path

Head over to his blog for solution in C# and JavaScript.

int.SubString() ?

How would you write a Substring function for an Integer?

Determine Hierarchy Name Based on Inconsistent Level

Below are sets of inconsistent arrays that represents level in hierarchy:

  • [0, 1, 2]
  • [0, 1]
  • [0]

The order of hierarchy is (from the top to the bottom):

  • Director
  • Manager
  • Employee

The highest number in the array represents the bottom level in the hierarchy. The lowest number in the array represents higher level in the hierarchy.

So, given [0, 1, 2]: 0 means Director, 1 means Manager and 2 means Employee. And given [0, 1]: 0 means Manager and 1 means Employee.

What’s the most efficient way to assign LevelName property in the following data set. The answer doesn’t have to use specific programming language.

[{
    Fullname: "Bob",
    ReportTo: "",
    Level: "0",
    LevelName: ""
},{
    Fullname: "John",
    ReportTo: "Bob",
    Level: "1",
    LevelName: ""
},{
    Fullname: "Sally",
    ReportTo: "John",
    Level: "2",
    LevelName: ""
},{
    Fullname: "David",
    ReportTo: "John",
    Level: "2",
    LevelName: ""
},{
    Fullname: "Rachel",
    ReportTo: "Bob",
    Level: "1",
    LevelName: ""
},{
    Fullname: "Peter",
    ReportTo: "Rachel",
    Level: "2",
    LevelName: ""
}]

What is the Best and Fastest Way to Flatten Data?

Given the following data set, what’s the best and fastest way to flatten them? This can be achieved with LINQ, SQL, C#, or whatever else you prefer.

001 12/5/2013 113 143 11143 44 673
001 12/6/2013 113 143 11143 44 673
001 12/7/2013 113 143 11143 44 673
001 12/8/2013 113 143 11143 44 673
001 12/9/2013 113 143 11143 44 673
001 12/10/2013 113 143 11143 44 673
002 12/5/2013 113 143 11143 44 673
002 12/6/2013 113 143 11143 44 673
002 12/7/2013 113 143 11143 44 673
002 12/8/2013 113 143 11143 44 673
002 12/9/2013 113 143 11143 44 673
002 12/10/2013 113 143 11143 44 673

Desired result:

001 12/5/2013 113 143 11143 44 673 12/6/2013 113 143 11143 44 673 12/7/2013 113 143 11143 44 673 12/8/2013 113 143 11143 44 673 12/9/2013 113 143 11143 44 673 12/10/2013 113 143 11143 44 673
002 12/5/2013 113 143 11143 44 673 12/6/2013 113 143 11143 44 673 12/7/2013 113 143 11143 44 673 12/8/2013 113 143 11143 44 673 12/9/2013 113 143 11143 44 673 12/10/2013 113 143 11143 44 673

Compare Two URL Strings

URL String Compare

What is the best approach to compare two URLs and determine if they are the same or not?

For example:
https://stack247.wordpress.com and stack247.wordpress.com are the same URL.
https://stack247.wordpress.com and stack247.wordpress.com are the same URL.
https://stack247.wordpress.com/tag/interview-question/ and stack247.wordpress.com/tag are NOT the same URL.

Android Keyboard Auto Suggest Design

This time tech challenge is about designing Android keyboard auto suggest.

Android keyboard auto suggest is a feature to suggest words that match what you have typed even if there’s typo.

android-keyboard-auto-suggest-design

As the above screenshot shows, Android system suggests ‘Thus’ and ‘This’ words when I type ‘Rgua’. Although ‘Rgua’ is a typo, it knows what I intend to type (which is ‘This’) because the letters’ position in ‘Rgua’ are as if I am typing ‘This’.

There is another trick to this feature. That is to suggest correct words in absence of space. For example, if I type ‘mytournament’ or ‘mybtournament’ or ‘myctournament’, the system will suggest ‘my tournament’. Notice it recognizes ‘b’ and ‘c’ as a space.

If you are to design / architect this, what’s your approach?

String Join Array Without Converting to List

I have the following code:


var fullName = "John Doe Smith";

var names = fullName.Split(' ');

var firstName = names[0];

//var lastName = ...

How can we populate lastName variable without converting names[] to List<T>?