Created
October 27, 2022 19:00
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Task with longest chain
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import pytest | |
def longest_chain_of_words( | |
inputs: tuple[str, ...], | |
) -> int: | |
"""Find the longest chain of words within an array matching the rule. | |
The rule is: | |
Removing one character from a word, gives you a new word | |
which is in the remaining part of the array of words. | |
Example: | |
Array: | |
("a", "b", "ba", "bca", "bda", "bdca") | |
Answer is 4, because: | |
bd~c~a == bda (present in the array), +1 to the chain | |
b~d~a == ba, +1 to the chain | |
b~a~ == b, +1 to the chain | |
chain length is 4 | |
""" | |
assert inputs, "expect not empty tuple of strings" | |
# TODO finish the implementation | |
@pytest.mark.parametrize( | |
("inputs", "exp"), | |
( | |
(("a", "b", "ba", "bca", "bda", "bdca"), 4), | |
(("a", "b", "ba", "bca", "bdca", "bda"), 4), | |
(("a", "b", "bac", "bca", "bda", "bdca"), 2), | |
(("a", "b", "and", "an", "bac", "bca", "bda", "bdca"), 3), | |
(("a", "and", "an", "bear"), 3), | |
(("a", "b"), 1), | |
(("a", "a"), 1), | |
(("x", "yz"), 1), | |
(("x",), 1), | |
(("x", "xz"), 2), | |
(("xz", "x"), 2), | |
), | |
) | |
def test_case(inputs, exp): | |
assert longest_chain_of_words(inputs) == exp |
My solution in python looks like this:
from functools import partial
import pytest
def longest_chain_of_words(
inputs: tuple[str, ...],
) -> int:
"""Find the longest chain of words within an array matching the rule.
The rule is:
Removing one character from a word, gives you a new word
which is in the remaining part of the array of words.
Example:
Array:
("a", "b", "ba", "bca", "bda", "bdca")
Answer is 4, because:
bd~c~a == bda (present in the array), +1 to the chain
b~d~a == ba, +1 to the chain
b~a~ == b, +1 to the chain
chain length is 4
"""
assert inputs, "expect not empty tuple of strings"
inputs_sorted = sorted(inputs, key=len)
def get_longest_path(
chain: str,
chains: list[str],
current_level: int,
max_level: int,
) -> int:
if len(chain) == 1 or len(chains) == 0:
return max_level
def slice_and_join(idx: int) -> str:
return chain[:idx] + chain[idx + 1 :]
def exists_in_chains(chain_candidate: str) -> bool:
return chain_candidate in chains
try:
return max(
map(
partial(
get_longest_path,
chains=chains,
current_level=current_level + 1,
max_level=max(current_level + 1, max_level),
),
filter(
exists_in_chains,
map(slice_and_join, range(len(chain))),
),
)
)
# in case the map container is empty, max raises ValueError
except ValueError:
return get_longest_path(chains.pop(), chains, 1, max_level)
return get_longest_path(inputs_sorted.pop(), inputs_sorted, 1, 1)
@pytest.mark.parametrize(
("inputs", "exp"),
(
(("a", "b", "ba", "bca", "bda", "bdca"), 4),
(("a", "b", "ba", "bca", "bdca", "bda"), 4),
(("a", "b", "bac", "bca", "bda", "bdca"), 2),
(("a", "b", "and", "an", "bac", "bca", "bda", "bdca"), 3),
(("a", "and", "an", "bear"), 3),
(("a", "b"), 1),
(("a", "a"), 1),
(("x", "yz"), 1),
(("x",), 1),
(("x", "xz"), 2),
(("xz", "x"), 2),
),
)
def test_case(inputs, exp):
assert longest_chain_of_words(inputs) == exp
Thank you @yruslan
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This can be further optimized, but general approach in Scala from me is like this: