bool canConstruct(string ransomNote, string magazine) {

unordered_map<char, int> m;

for(int i=0; i<magazine.size(); i++) {

m[magazine[i]]++;

}

for (int i=0; i<ransomNote.size(); i++) {

char c = ransomNote[i];

if (m[c] <=0 ) return false;

m[c]--;

}

return true;

}