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zip_longest and yield solution in Clear category for Swap Nodes by rossras
from itertools import zip_longest
def swap_nodes(a):
odd_sentinel = object()
it = iter(a)
for a, b in zip_longest(it, it, fillvalue=odd_sentinel):
if b is not odd_sentinel:
yield b
yield a
if __name__ == '__main__':
print("Example:")
print(list(swap_nodes([1, 2, 3, 4])))
# These "asserts" are used for self-checking and not for an auto-testing
assert list(swap_nodes([1, 2, 3, 4])) == [2, 1, 4, 3]
assert list(swap_nodes([5, 5, 5, 5])) == [5, 5, 5, 5]
assert list(swap_nodes([1, 2, 3])) == [2, 1, 3]
assert list(swap_nodes([3])) == [3]
assert list(swap_nodes(["hello", "world"])) == ["world", "hello"]
print("Coding complete? Click 'Check' to earn cool rewards!")
Feb. 13, 2020
