题解 | #字符流中第一个不重复的字符#

//采用两个集合来解决这个问题，然后借助包含，添加，移除这三个函数

public class Solution {

public ArrayList<Character> store = new ArrayList<>();
public ArrayList<Character> temp = new ArrayList<>();

public void Insert(char ch) {
    if(!store.contains(ch)&&!temp.contains(ch)){
        store.add(ch);
    }else {
        store.remove((Character) ch);
        temp.add(ch);
    }
}

public char FirstAppearingOnce(){
    if(store.size()==0){
        return '#';
    } else {
        return store.get(0);
    }
}

}