|
| 1 | +""" |
| 2 | +Project Euler Problem 117: https://projecteuler.net/problem=117 |
| 3 | +
|
| 4 | +Using a combination of grey square tiles and oblong tiles chosen from: |
| 5 | +red tiles (measuring two units), green tiles (measuring three units), |
| 6 | +and blue tiles (measuring four units), |
| 7 | +it is possible to tile a row measuring five units in length |
| 8 | +in exactly fifteen different ways. |
| 9 | +
|
| 10 | + |grey|grey|grey|grey|grey| |red,red|grey|grey|grey| |
| 11 | +
|
| 12 | + |grey|red,red|grey|grey| |grey|grey|red,red|grey| |
| 13 | +
|
| 14 | + |grey|grey|grey|red,red| |red,red|red,red|grey| |
| 15 | +
|
| 16 | + |red,red|grey|red,red| |grey|red,red|red,red| |
| 17 | +
|
| 18 | + |green,green,green|grey|grey| |grey|green,green,green|grey| |
| 19 | +
|
| 20 | + |grey|grey|green,green,green| |red,red|green,green,green| |
| 21 | +
|
| 22 | + |green,green,green|red,red| |blue,blue,blue,blue|grey| |
| 23 | +
|
| 24 | + |grey|blue,blue,blue,blue| |
| 25 | +
|
| 26 | +How many ways can a row measuring fifty units in length be tiled? |
| 27 | +
|
| 28 | +NOTE: This is related to Problem 116 (https://projecteuler.net/problem=116). |
| 29 | +""" |
| 30 | + |
| 31 | + |
| 32 | +def solution(length: int = 50) -> int: |
| 33 | + """ |
| 34 | + Returns the number of ways can a row of the given length be tiled |
| 35 | +
|
| 36 | + >>> solution(5) |
| 37 | + 15 |
| 38 | + """ |
| 39 | + |
| 40 | + ways_number = [1] * (length + 1) |
| 41 | + |
| 42 | + for row_length in range(length + 1): |
| 43 | + for tile_length in range(2, 5): |
| 44 | + for tile_start in range(row_length - tile_length + 1): |
| 45 | + ways_number[row_length] += ways_number[ |
| 46 | + row_length - tile_start - tile_length |
| 47 | + ] |
| 48 | + |
| 49 | + return ways_number[length] |
| 50 | + |
| 51 | + |
| 52 | +if __name__ == "__main__": |
| 53 | + print(f"{solution() = }") |
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