?Given? an ?arbitrary? ransom? note? string ?and ?another ?string ?containing ?letters from? all ?the ?magazines,? write ?a ?function ?that ?will ?return ?true ?if ?the ?ransom ? note ?can ?be ?constructed ?from ?the ?magazines ; ?otherwise, ?it ?will ?return ?false. ??

Each ?letter? in? the? magazine ?string ?can? only ?be? used ?once? in? your ?ransom? note.

Note:
You may assume that both strings contain only lowercase letters.

canConstruct("a", "b") -> falsecanConstruct("aa", "ab") -> falsecanConstruct("aa", "aab") -> true

class Solution {public:    bool canConstruct(string ransomNote, string magazine) {        map<char, int> map;        for (auto &e : ransomNote)        {            ++map[e];        }        for (auto &e : magazine)        {            if (map.find(e) != map.end())            {                if (--map[e] == 0)                {                    map.erase(e);                }            }        }        return !map.size();    }};

LeetCode 383. Ransom Note