383. 赎金信 --力扣 --JAVA

class Solution {
    public boolean canConstruct(String ransomNote, String magazine) {
        Map<Character,Integer> data = new HashMap<>();
        for(int i = 0; i < ransomNote.length(); i++){
            char temp = ransomNote.charAt(i);
            Integer num = data.getOrDefault(temp, 0);
            num += 1;
            data.put(temp, num);
        }
        for(int i = 0; i < magazine.length(); i++){
            char temp = magazine.charAt(i);
            Integer num = data.get(temp);
            if(num != null){
                if(num == 1){
                    data.remove(temp);
                } else {
                    data.put(temp, num - 1);
                }
            }
        }
        return data.isEmpty();
    }
}