Coding Interview: King And Queen On A Chessboard - Whiteboard Wednesday

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Welcome to Whiteboard Wednesday where I do software engineering interview problems on the whiteboard in a real interview setting.
Today's problem is on how to navigate on a 2D matrix in form of a chessboard.
Leave a comment on what problem you want us to cover next!

[@michaelluong7387]

An alternative way to solving the diagonal case is to find the slope by computing (y2-y1)/(x2-x1). If that is equal to 1, then return True.

[@JayPatel12928]

(Or -1) True !

[@anujchoudhary3126]

Thank you so much man. More than this video your comment saved by A** today. Thanks a lot

[@stewartzayat7526]

This was a nice and fun problem! I hope I will get a question like this on my interview.

[@franciskisiara]

The biggest assumption here is that the interviewee knows how to play chess.

[@hahafender]

Awesome videos man! Thank you!!

[@aaroncontreras2653]

Shouldn't the validate function check for && and not || since all conditions need to be met for a valid coordinate?

[@stephanbranczyk8306]

Good catch

[@rafaelcupello2549]

Thanks!!!! Very good!!!!

[@IrfanBaqui]

Glad you liked it!

[@EmulatE42]

For diagonal just substract x1 x2 and y1 y2, and see if two result are same. Also maybe use abs just to be sure xD

[@EmulatE42]

Oh nevermind

[@hymnsoftheheart]

Seems like there's an assumption here about the coordinate system in use here that should have been clarified. The diagonal case would have been easy (equal deltas) if the origin of the coordinate system is in the lower left corner.

[@stephanbranczyk8306]

The origin of the coordinate system threw me off too, but it doesn't actually change the nature of the solution. The queen can attack on either diagonal. And the king does not have to be at a higher elevation than the queen, for instance, he could below the queen on one of her diagonals. In the end, the placement of the origin doesn't really matter.

[@sojuthomas7727]

hi Irfan for diagonal checking,how about incrementing both x and y coordinate by one unit and repeat the step until matching coordinate found. is that completely cool..??

[@DiapaYY]

that is slower but would work if you did it in all directions.

[@MahmoudAtef]

Simply you can say tan(45) = 1 which means |kx-qx| / |ky-qy| ==1 and that's it

[@eric325]

The slope formula m = delta y / delta x would have been been helpful. In order for the queen to be able to attack the king diagonally, m must be 1.

[@DiapaYY]

You'd need floating point though blah

[@FistroMan]

Diagonal: Qx － Kx ＝＝ Qy －Ky The order.. im not sure, does not matter

[@kunalfarmah43]

we could just use the logic of safe positions in the n-queen problem

[@gyulanyirfalvi7013]

at the end of the video your validation goes like this: If EL is integer OR (???) EL >= 1 OR EL

[@IrfanBaqui]

gyula nyirfalvi you're right, good catch.

[@augustusmb]

Yes

[@JayPatel12928]

No you're not, that is exactly when I paused the vid.

[@siddharthmanumusic]

why not just proceed one block x and one block y, in each of the 4 diagonal directions. It's so easy

[@abhisheksable622]

which company asks this question 😂

[@stefano8936]

mm mh