如何按值对 STL 映射进行排序?

How can I sort an STL map by value?(如何按值对 STL 映射进行排序?)

问题描述

如何实现 STL 映射按值排序?

How can I implement STL map sorting by value?

例如，我有一个地图 m:

For example, I have a map m:

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

我想按 m 的值对该地图进行排序.所以，如果我打印地图，我想得到如下结果:

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

如何以这种方式对地图进行排序?有什么办法可以用排序的值处理键和值吗?

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?

推荐答案

您可以构建第二个映射，将第一个映射的值作为键，将第一个映射的键作为值.

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

这仅在所有值都不同时才有效.如果您不能假设这一点，那么您需要构建一个多地图而不是地图.

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

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