JZ54 字符流中第一个不重复的字符

https://www.nowcoder.com/practice/00de97733b8e4f97a3fb5c680ee10720

第一次解：

直接使用暴力法解

import java.util.*;

public class Solution {
    LinkedHashMap<Character, Integer> map = new LinkedHashMap<>();
    char single = '#';

    public void Insert(char ch) {
        if (!map.containsKey(ch)) {
            map.put(ch, 1);
            if (single == '#') {
                single = ch;
            }
        } else {
            map.put(ch, map.getOrDefault(ch, 1) + 1);
            if (ch == single) {
                single = '#';
                // 这里取第一个不重复的值
                for (Map.Entry<Character, Integer> entity : map.entrySet()) {
                    if (entity.getValue() == 1) {
                        single = entity.getKey();
                        break;
                    }
                }
            }
        }
    }

  //return the first appearence once char in current stringstream
    public char FirstAppearingOnce() {
        return single;
    }
}