Informatics2-2018/Lab09
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− | == | + | == Finite-state machine== |
− | === | + | === Parenthesis === |
− | + | Given a string, replace the enclosed parts of the string with a '''$''' character. | |
+ | A formula is enclosed if it is surrounded by parenthesis. For example: | ||
− | + | (xc)aa(c(b)) -> $$$$aa$$$$$$ | |
− | + | ||
− | + | Note that the parenthesis can be enclosed into each other. | |
− | + | === Keystrokes === | |
− | + | Download the following text file: [http://sandbox.hlt.bme.hu/~gaebor/ea_anyag/Info2/raw_data.txt raw_data.txt] | |
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− | + | ||
− | + | This file contains keystroke data when someone was typing. | |
+ | The interesting part starts from the 5<sup>th</sup> line: | ||
− | + | * The first column is an event: '''keydown''' or '''keyup''' (others are irrelevant now) | |
+ | * The next three numbers encode the key, actually the second one is important (third column). | ||
+ | * The fourth column refers to capital or lowercase, but thats also irrelevant now. | ||
+ | * The last one is a timestamp, the number of milliseconds elapsed since January 1<sup>st</sup>, 1970. | ||
− | + | The exercise is to process the keystrokes and reconstruct the typed text. | |
− | + | Mind that there is a SHIFT key in the data. | |
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− | + | '''Hint:''' | |
− | + | * Store a dictionary of keys which are pressed at a given time. | |
− | + | * if a key is released, and it was in the dictionary, then that letter was entered. | |
− | + | ** in this case, erase that key from the dictionary. | |
− | * | + | * store the state of the SHIFT key (up or down) |
− | * | + | * There is also a BACKSPACE key! |
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A lap 2018. április 18., 09:54-kori változata
Tartalomjegyzék |
Exercises
Dynamic programming
Pascal triangle
Write a function that returns the nth row of the Pascal triangle as a list.
Knight
Let's say that you have a knight on the chessboard. Calculate how many steps does it take to optimally reach the other places on the board.
Write a function knight(x,y) where the parameters are the x, y coordinates of the initial place. Return an 8-by-8 table of integers containing the minimum number of steps to reach that position. For example the initial state should have 0 on it.
Use a dynamic programming table!
Paint Bucket Tool
Save the following "text" as a list of lists in python!
Write a function fill(x,y) which fills a territory starting with the given coordinates, like the bucket tool in Paint.
Starting from the (x, y) coordinate replace . with #, if you encounter a # then stop. Do this recursively for every neighbor of the given point. This will fill out an enclosed territory.
..................................... ...#######################........... ...#.....................#........... ...#.....................#........... ...#.....................#........... ...#.....................#........... ...#.....................#........... ...#.....................#######..... ...###.................##......#..... ...#..##.............##........#..... ...#....##.........##..........#..... ...#......##.....##............#..... ...#........#####..............#..... ...#........#..................#..... ...#.......##..................#..... ...#.....##....................#..... ...#...##......................#..... ...#############################..... ..................................... ..................................... ..................................... .....................................
Finite-state machine
Parenthesis
Given a string, replace the enclosed parts of the string with a $ character. A formula is enclosed if it is surrounded by parenthesis. For example:
(xc)aa(c(b)) -> $$$$aa$$$$$$
Note that the parenthesis can be enclosed into each other.
Keystrokes
Download the following text file: raw_data.txt
This file contains keystroke data when someone was typing. The interesting part starts from the 5th line:
- The first column is an event: keydown or keyup (others are irrelevant now)
- The next three numbers encode the key, actually the second one is important (third column).
- The fourth column refers to capital or lowercase, but thats also irrelevant now.
- The last one is a timestamp, the number of milliseconds elapsed since January 1st, 1970.
The exercise is to process the keystrokes and reconstruct the typed text. Mind that there is a SHIFT key in the data.
Hint:
- Store a dictionary of keys which are pressed at a given time.
- if a key is released, and it was in the dictionary, then that letter was entered.
- in this case, erase that key from the dictionary.
- store the state of the SHIFT key (up or down)
- There is also a BACKSPACE key!