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) {
int r[26] = {0};
int m[26] = {0};
for(char ch : ransomNote)
r[ch - 'a']++;
for(char ch : magazine)
m[ch - 'a']++;
for(int i = 0; i < 26; ++i){
if(r[i] > m[i])
return false;
}
return true;
}
};