tvl-depot/users/wpcarro/scratch/facebook/product-of-all-other-numbers.py

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from random import randint
from math import floor
# loop {forwards, backwards, up, down}
# through a table of values, [[a]].
def product(xs):
n = len(xs)
lhs = [1] * (n + 1)
for i in range(1, n):
lhs[i] = lhs[i - 1] * xs[i - 1]
rhs = [1] * (n + 1)
for i in range(n - 1, 0, -1):
rhs[i] = rhs[i + 1] * xs[i]
result = []
for i in range(n):
result.append(lhs[i] * rhs[i + 1])
return result
def computed_expected(xs):
product = 1
for x in xs:
product *= x
return [floor(product / x) for x in xs]
xs = [randint(1, 10) for _ in range(5)]
expected = computed_expected(xs)
result = product(xs)
print(xs, result, expected)
assert result == expected
print("Success!")
print(product([2, 4, 3, 10, 5]))