Join David Powers for an in-depth discussion in this video Detecting horizontal attacks programmatically, part of Code Clinic: PHP.
- In Chess, queens can attack…horizontally, vertically and diagonally.…We've eliminated the first two possibilities by using…binary numbers to represent each row.…There are eight binary numbers, each with only one bit set.…This ensures no two queens are ever…in the same row or column, it's easier to see…if you remove the zeroes.…That means that we only have to check for diagonal attacks.…Let's say there is a queen in the fifth column…of the fourth row, if we check the board row by row…beginning at the top, we need to search…for potential attacks only upwards and left…and upwards and right, diagonal attacks…from the adjacent row come from the column…on either side of the target, attacks from two rows away…come from squares two columns away and so on.…
Diagonals are always an equal number…of rows and columns from the target.…Let's see how we can test adjacent rows.…This is the first row with a binary number…from one of the permutations, we need…to test it against the second row.…Diagonal attacks against the queen in the second row…
Author
David Powers
Updated
12/16/2014Released
7/15/2014David introduces challenges and provides an overview of his solutions in PHP. Challenges include topics such as statistical analysis, searching directories for images, and accessing peripheral devices.
Visit other courses in the series to see how to solve the exact same challenges in languages like C#, C++, Java, Python, and Ruby.
Skill Level Intermediate
Duration
Views
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Introduction
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Welcome1m 18s
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Using the exercise files1m 56s
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Problem One: Statistical Analysis
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Overview of my solution3m 22s
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Setting up the database4m 55s
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Processing the full-year records10m 49s
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Processing individual days6m 54s
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Keeping the data up to date4m 27s
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Creating a web service6m 21s
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Getting the required data6m 50s
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Problem Two: Image Analysis
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Identify the image subset3m 14s
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Overview of my solution3m 19s
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Setting up the files2m 43s
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Generating the thumbnails7m 49s
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Finding the cropped images7m 13s
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Problem Three: Eight Queens
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Overview of my solution3m 48s
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Rotating the chessboard4m 59s
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Problem Four: Accessing Peripherals
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Overview of my solution2m 1s
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Using the Web Audio API2m 47s
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Creating the tone generator7m 39s
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Problem Five: Recursion and Directories
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Overview of my solution3m 24s
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Finding the images5m 30s
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Extracting XMP metadata6m 22s
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Problem Six: Building the Web
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Building the web1m 47s
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Overview of my solution1m 50s
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Video: Detecting horizontal attacks programmatically