LeetCode: 383 Ransom Note(easy)

题目：

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

代码:

class Solution {
public:
    bool canConstruct(string ransomNote, string magazine) {
        if (ransomNote == "")
            return true;
        for (auto c : ransomNote){
            int position = magazine.find_first_of(c); 
            if (position != magazine.npos)
                magazine.erase(position, 1);
            else
                return false;        
        }
       return true;    
    }
};

别人的：

class Solution {
public:
    bool canConstruct(string ransomNote, string magazine) {
        int mp[26] = {0};
        for(auto c : magazine) {
            mp[c - 'a']++;
        }
        for(auto r : ransomNote) {
            mp[r - 'a']--;
            if(mp[r - 'a'] < 0) return false;
        }
        return true;
    }
};