Question

How can I implement STL map sorting by value?

For example, I have a map m:

map<int, int> m;
m[1] = 10;
m[2] = 5;
m[4] = 6;
m[6] = 1;

I’d like to sort that map by m‘s value. So, if I print the map, I’d like to get the result as follows:

m[6] = 1
m[2] = 5
m[4] = 6
m[1] = 10

How can I sort the map in this way? Is there any way that I can deal with the key and value with sorted values?

Answer 1

You can build a second map, with the first map’s values as keys and the first map’s keys as values.

This works only if all values are distinct. If you cannot assume this, then you need to build a multimap instead of a map.