leetcode-383. Ransom Note

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

这题求  ransomNote 中的字母是否都在 magazine 中，不要求顺序一致

所以直接将 magazine 转换为 StringBuffer ，看 ransomNote 的字符的下标是否不为-1，存在即删除。不存在即返回false。

solution：

class Solution {
    public boolean canConstruct(String ransomNote, String magazine) {
        StringBuffer Strb = new StringBuffer(magazine);
        for (int i = 0; i < ransomNote.length(); i++) {
            int n = Strb.indexOf(String.valueOf(ransomNote.charAt(i)));
            if(n!=-1) Strb.deleteCharAt(n);
            else return false;
        }
        return true;
    }
}