RansomNote

 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

 1  1 public class Solution {
 2  2    public boolean canConstruct(String ransomNote, String magazine) {
 3  3         int[] arr = new int[26];
 4  4         for (int i = 0; i < magazine.length(); i++) {
 5  5             arr[magazine.charAt(i) - 'a']++;
 6  6         }
 7  7         for (int i = 0; i < ransomNote.length(); i++) {
 8  8             if(--arr[ransomNote.charAt(i)-'a'] < 0) {
 9  9                 return false;
10 10             }
11 11         }
12 12         return true;
13 13     }
14 14 }

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