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.

手写以ch-'a'建立的map可以更快，不过懒得写了。

class Solution {
    public boolean canConstruct(String ransomNote, String magazine) {
        HashMap map = new HashMap<>();
        for(int i = 0 ;i