Friends set clear solution for How to Find Friends by hanpari - python coding challenges

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Friends set solution in Clear category for How to Find Friends by hanpari

def check_connection(edges, first, last):
    path = {first}
    check = 0
    # All points who can be acceseed from "first"
    # are put in path set.
    # At the end end "last" is checked if is in path set.
    while(len(path) > check):
        check = len(path)
        # this part can be easily optimized to avoid 
        # iterating through edges already accepted in path set.
        # I skipped this to keep my solution 
        # clear and easy to understand
        for edge in edges: 
            one, two = edge.split("-")
            if one in path or two in path:
                path.add(one)
                path.add(two)
    else:
        return last in path


if __name__ == '__main__':
    #These "asserts" using only for self-checking and not necessary for auto-testing
    assert check_connection(
        ("dr101-mr99", "mr99-out00", "dr101-out00", "scout1-scout2",
         "scout3-scout1", "scout1-scout4", "scout4-sscout", "sscout-super"),
        "scout2", "scout3") == True, "Scout Brotherhood"
    assert check_connection(
        ("dr101-mr99", "mr99-out00", "dr101-out00", "scout1-scout2",
         "scout3-scout1", "scout1-scout4", "scout4-sscout", "sscout-super"),
        "super", "scout2") == True, "Super Scout"
    assert check_connection(
        ("dr101-mr99", "mr99-out00", "dr101-out00", "scout1-scout2",
         "scout3-scout1", "scout1-scout4", "scout4-sscout", "sscout-super"),
        "dr101", "sscout") == False, "I don't know any scouts."

June 28, 2014

Comments:

virajh on May 1, 2015, 6:31 a.m.
Wow your solution is incredibly simple!

hanpari on May 1, 2015, 9:50 a.m.
Thank you. It is thanks to set. It is invaluable datastructure which is underused.

Ligulf on July 6, 2015, 8:39 a.m.
Great solution, very easy to understand for noobs like myself.

hanpari on July 7, 2015, 12:10 p.m.
Thank you, this is from my times when I tried to be as clear as possible. Just use sets and you will be OK :)

vit.aborigen on Jan. 30, 2019, 8:52 a.m.
This solution deserves to take 1st place

hanpari on Jan. 30, 2019, 3:51 p.m.
Thank you. Actually, it is not that good. The missing optimization in the middle is quite distressing.

ann3leo on July 26, 2021, 3:08 p.m.
I really like 'while-else' using here. Elegant!

hanpari on July 26, 2021, 5:36 p.m.
Thank you, but in this particular case, it is neither elegant nor correct usage of the else keyword. Frankly, I do not use this construction at all, but the gist is as follows: <pre class='brush: python'>while True: break else: print("If a break occurs in a while loop, this prints nothing!") </pre> Since there is no break in my code, the else statement is redundant and incorrect. A simple return should suffice.

ann3leo on July 27, 2021, 12:08 p.m.
Thank you for your explanation. Now I see that simple return will do the job.

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