Informatics2-2018/Lab09
Tartalomjegyzék |
Exercises
Dynamic programming
Pascal triangle
Write a function that returns the nth row of the Pascal triangle as a list.
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.
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!
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!
- You can see the keycodes here