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

public class Solution {
    public boolean canConstruct(String ransomNote, String magazine) {
        int[] arr = new int[26];
        for(int i=0;i<magazine.length();i++)
        {
            char c = magazine.charAt(i);
            arr[c-'a']++;
        }
        
        for(int i=0;i<ransomNote.length();i++)
        {
            char c = ransomNote.charAt(i);
            arr[c-'a']--;
            if(arr[c-'a']<0) return false;
        }
        
        return true;
    }
}

reference: 

https://discuss.leetcode.com/topic/53864/java-o-n-solution-easy-to-understand/3