MarioYC's blog

TJU 3783 Cards
By MarioYC, 13 months ago, In English,

Hi everyone, so I found this problem today, and it seems like a really obvious bipartite matching, but I've been getting TLE in it. Is there some faster way to solve it?

 
 
 
 

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13 months ago, # |
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O(VE) bipartite matching algorithm obviously gets TLE on dense graph with such limits. I think solution which runs in O(sqrt(v) * E) will pass. For example you can use "Hopcroft–Karp algorithm".

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    13 months ago, # ^ |
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    Sorry, forgot to say I used Hopcroft-Karp.

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      13 months ago, # ^ |
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      Strange... Show your code, maybe i can help. Solution with O(N ^ 2.376) exists, but i think Hopcroft-Karp must pass.

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        13 months ago, # ^ |
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        Here it is: http://pastebin.com/3RH9u4SN

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          13 months ago, # ^ |
          ← Rev. 2   Vote: I like it 0 Vote: I do not like it

          Your algorithm works in O(VE) time and it isn't Hopcroft-Karp. Just try this testcase: 500 500

          2 2 2 2 2 ... (500 times)

          2 2 2 2 2 ... (500 times)

          Copy this a few times and then add "0 0". Your algorithm will work more then 5 seconds (and will get TLE).

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            13 months ago, # ^ |
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            Thanks, I found the mistake, I was using the || operator instead of |= when updating the variable change. With this change it still isn't Hopcroft karp because i'm not taking shortest paths, but that only makes it a bit slower.

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13 months ago, # |
← Rev. 2   Vote: I like it +5 Vote: I do not like it

Dinnic works here, my solution accepted in 4.86 seconds.

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