“armanriazirustcollectionhashmapavoid_of_duplicate” Ответ

armanriazirustcollectionhashmapavoid_of_duplicate

 Default setting which is using insert you will have any duplicated key or val. 
 map.insert(key, "some value".into());
 but when we use entry(word).or_insert(0) that will make avoid duplicated k/v.
 let mut map = HashMap::<CompoundKey, String>::new();
 let tmp = map.entry(word).or_insert(0);