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Foysal_Ahmmed's blog

By Foysal_Ahmmed, history, 21 month(s) ago, In English,

I am getting Memory limit exceeded for this problem C. Dijkstra? But why I can not understand this. My Solution

 
 
 
 
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21 month(s) ago, # |
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The size of queue is getting very large during execution you can either use set like this solution and clear the entry for v line number 29 this will restrict the size of set to at max O(N) http://codeforces.com/contest/20/submission/43596615

or like this solution you can free some memory by clearing the vectors you are not going to use. http://codeforces.com/contest/20/submission/43596568

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    21 month(s) ago, # ^ |
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    But I can not understand how the set (is it work like priority queue ? )work in here please can you explain it .

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      21 month(s) ago, # ^ |
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      the purpose of priority queue is to extract the minimum element. In set the 1st element is the smallest element. While set provide an option to erase a element while the same operation is not supported in priority queue. priority queue is implemented as Heap while set is implemented as red black tree(Binary search tree)

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        21 month(s) ago, # ^ |
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        Ok that's great I understood now thank you .

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          21 month(s) ago, # ^ |
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          Actually, set has higher overhead compared to priority queue due to additional book-keeping such as balancing. In this case, road_to_red was able to achieve a much better runtime and memory limit because of the fact that we can efficiently search for and remove irrelevant nodes from the set, whereas we can't do so in a priority queue.

          Anyway, I think that your main problem is that you didn't terminate your loop, in your dijkstra shortest path implementation, when your destination has been visited. As such, a lot of irrelevant nodes might be stored in the priority queue and cause the MLE to occur.

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21 month(s) ago, # |
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maybe the use of priority queue with greater feature , i suggest to use negative cost instead , that's my solution:https://codeforces.com/contest/20/submission/43549173