383. Ransom Note
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") -> false canConstruct("aa", "ab") -> false canConstruct("aa", "aab") -> true
class Solution { public: bool canConstruct(string ransomNote, string magazine) { unordered_map<char,int> hashMap; for(char ch : magazine){ ++hashMap[ch]; } for(char ch :ransomNote){ if(--hashMap[ch]<0) return false; } return true; } };