LeetCode之Ransom Note

1、題目

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

2、代碼實作

public class Solution {
        public  boolean canConstruct(String ransomNote, String magazine) {
           if (magazine == null)
               return false;
           if (ransomNote == null)
               return false;
           if (ransomNote.length() == 0 && magazine.length() == 0) 
               return true;
           List<Character> list = new ArrayList<Character>();
           for (char c : magazine.toCharArray()) {
               list.add(Character.valueOf(c));
           }
           if (ransomNote.length() == magazine.length()) {
               for (int i = 0; i < ransomNote.length(); i++) {
                   if (!list.remove(Character.valueOf(ransomNote.charAt(i)))) {
                       return false;
                   }
               }
               return true;
           } else {
               for (int i = 0; i < ransomNote.length(); i++) {
                   if (!list.remove(Character.valueOf(ransomNote.charAt(i)))) {
                       return false;
                   }
               }
               if (list.size() > 0) {
                   return true;
               }
           }
           return false;
    }
}