c++ - Reverse map lookup

Question

I have a 1 to 1 map. What's the best way to find keys from values,

i.e.

For examples if the map is this

KEY VALUE

a    1
b    2
c    3 
d    4

I want to be able to find that key corresponding to 3 is C.

Thanks!

Answer 1

There isn't much you can do about it. Your have options to work with two maps, use multi-key map like one from Boost Multi-Index library, or do linear search.

UPDATE: The most lightweight out of the box solution seems to be Boost.Bimap, which stands for bi-directional map.