katas

This is a place to keep my katas: whetstones for problem-solving and technical thought.

Contents

Kata0001

Implement a function that takes a list of all-caps cardinal directions ("NORTH", "SOUTH", "EAST", "WEST") and simplifies them, cancelling out opposing pairs.

Kata0002

Given a square matrix, an x_start_index and a y_start_index, return a 3 * 3 subsquare from the matrix. Matrix dimensions are always minimum 3 * 3. If either start index is too high, give None in the out-of-bounds positions.

Kata0003

Create a ConnectFourGame class that keeps track of its state, with the methods:

• .get_board(), returning the current state of the board (initialized as a 7 * 6 matrix filled with None)
• .get_player(), returning a string indicating whether the current player is x or o (where x goes first)
• .play(), which takes a column index number as its argument and 'drops' a counter into that column, raising the exception This column is full if appropriate, and returning nothing
• .check_winner(), returning False if there is not yet any winner, or the winning player if 4 like counters are aligned either horizontally, vertically or diagonally

Kata0004

From TLDP: Write a bash script that reads each line of a target file, then writes the line back to stdout with an extra blank line following, effectively double-spacing the file. Check the script gets the necessary command-line argument (a filename), and whether the specified file exists. Modify the script to allow it:

• to triple-space the target file, and
• to remove all blank lines from the target file, single-spacing it.

Kata0005

Using the MongoDB Atlas training database's grades collection, and referring solely to data for class 256, extract a list of students who meet both of the following criteria:

• has at least one homework score above the class's homework average
• has at least one homework score at least 25% higher than the average of their own exam and quiz scores

Kata0006

From CodeKata.com: Working out answers in your head, estimate storage space used and time taken for a variety of values and operations.

Kata0007

From CodeKata.com: Given the text files weather.dat (containing weather data for Morristown, NJ for June 2002) and football.dat (containing results from the English Premier Leageue for 2001/2), write a program that outputs the day number with the smallest temperature spread, then a program that outputs the name of the team with the smallest difference in 'for' and 'against' goals. Both files require cleaning. Finally, factor out as much common code as possible.

Kata0008

Write a bash script that transfers a file to a new destination with rsync, appends '_TO_DELETE' to the original filename, and creates a symbolic link to the file's new destination. Show a progress bar, and assume names containing spaces are quoted. Modify the script to:

• take any number of filenames for transfer (as arguments $2, $3, $4, etc.),
• work with file names containing escaped characters, and
• ensure the symbolic link is created in the file's origin directory, not in the script's working directory.

Kata 0009

Given two integer lists sorted in ascending order, nums1 and nums2, and two integers, m and n, representing the number of elements to be used from the beginnings of nums1 and nums2 respectively, merge the two lists into a single list sorted in ascending order. nums1 is assumed to have a length of m + n, and the final sorted list should be produced by modifying nums1 in place, not by returning a new list.

Kata 0010

Shifting pointers: Keep CS fundamentals fresh by completing a series of tasks involving iteration over lists or strings.

1. Convert a string number in Roman numerals into an integer.

2. Given a list of integers and an integer val, remove all occurrences of val from the list in place. Return the number of elements not equal to val.

3. Given a list of integers and an integer target number, return the indices of two numbers in the list that add up to the target.

4. Given a list of integers sorted in ascending order, remove duplicates in place such that ascending order is retained. Return the number of unique elements.