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Asked: 2026-05-23T21:10:43+00:00

I have a mapping of String id -> Object . Apart from merely having

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I have a mapping of String id -> Object. Apart from merely having to insert and delete into this map, I would also need to find the id with the lowest x-value (x-value is a member in the Class from which the Object is instantiated).

Initially I thought I could just create another mapping x-value -> String id for this. But that does not help this much, because in case of Remove operation, I have to now anyway search this second map for a particular id (so we are back to the main problem itself now).

Any suggestions to do this efficiently? (time wise – memory is not a big constraint)

EDIT: I think I could just get the x-value from the id (for removal function) and remove from second map using the x-value. Another thing here – the x-value is a float. Good idea to use float as a key in a map ?? Maybe using fabs and a precision value could do the trick here for floating point comparisons ?

EDIT #2: Unfortunately I remembered why the above method might not work (I was busy with other stuff and forgot about this project for a while). The x-value for different map entries NEED NOT BE UNIQUE. String ID is the primary key. So I need to use a multimap and use equal_range.

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1 Answer

  1. Editorial Team

    Your solution of using an auxiliary map isn’t as bad as your post suggests.

    It is true that a removal operation would require a lookup in the second map. However, this lookup can be done in O(log n) time. This is unlikely to be a deal breaker. If it is, please post more details.

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