Java编程题目-12：字符串的construct

题目要求：

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") -> falsecanConstruct("aa", "ab") -> falsecanConstruct("aa", "aab") -> true

原题链接：请戳这里
解决代码如下：

public class Solution {    public boolean canConstruct(String ransomNote, String magazine) {        ArrayList<Character> ranList = getListFromArray(ransomNote);        ArrayList<Character> magList = getListFromArray(magazine);        // 循环从ransomNote中取出字符        for(int i=0;i<ranList.size();i++){            char c = ranList.get(i);            if(magList.contains(c)){                magList.remove(magList.indexOf(c));// *比对之后删掉该字符                continue;            }else{                return false;            }        }        return true;    }    // 将string转成list    public ArrayList<Character> getListFromArray(String string){        ArrayList<Character> list = new ArrayList<Character>();        char[] strArr = string.toCharArray();        for (char c : strArr) {            list.add(c);        }        return list;    }}

---

我的思路：
1. 从ransomNote中逐个取出字符
2. 再到magazine中去确认是否含有该字符
3. 如果magazine中包含该字符，则删掉magazine中的这个字符
4. 如果magazine中不含该字符，则返回false

为什么要删掉magazine中的对应字符？因为假如说ransomNote为“aaagbfrd”，而magazine为“aabgefdrtg“时，针对字符‘a’就会出现错误判断，当判断ransomNote中第三个‘a’时，实际应该是false，但是magazine中还是有‘a’与之对应，故会返回错误值true。