用int array记录可用字母数量
0的时候说明GG了
public boolean canConstruct(String ransomNote, String magazine) {
if(ransomNote.length() > magazine.length()) return false;
int[] letters = new int[26];
for(int n = 0; n < magazine.length();n++)
{
letters[magazine.charAt(n) - 'a']++;
}
for(int n = 0; n < ransomNote.length();n++)
{
if(letters[ransomNote.charAt(n) -'a'] != 0) letters[ransomNote.charAt(n)-'a']--;
else return false;
}
return true;
}