删除源文件中的注释

class Solution {

    public enum State{
        NORMAL, MULTI, SINGLE;
    }

    public enum Action{
        MULTI_START, MULTI_END, SINGLE_START, SINGLE_END, NONE;
    }

    public State getNextState(State state, char pre, char cur){
        // 判断动作
        Action action;
        if(pre == '/' && cur == '*') action = Action.MULTI_START;
        else if(pre == '/' && cur == '/') action = Action.SINGLE_START;
        else if(pre == '*' && cur == '/') action = Action.MULTI_END;
        else if(cur == '\n') action = Action.SINGLE_END;
        else action = Action.NONE;

        // 进行状态转移
        switch (state){
            case NORMAL:
                switch (action){
                    case SINGLE_START:
                        return State.SINGLE;
                    case MULTI_START:
                        return State.MULTI;
                    default:
                        return State.NORMAL;
                }
            case SINGLE:
                switch (action){
                    case SINGLE_END:
                        return State.NORMAL;
                    default:
                        return State.SINGLE;
                }
            case MULTI:
                switch (action){
                    case MULTI_END:
                        return State.NORMAL;
                    default:
                        return State.MULTI;
                }
        }
        return State.NORMAL;
    }

    public String solve(String source){
        char[] chars = source.toCharArray();
        StringBuilder sb = new StringBuilder();
        State pre = State.NORMAL;
        State state = State.NORMAL;
        sb.append(chars[0]);
        for(int i=1;i<chars.length;i++){
            pre = state;
            state = getNextState(state, chars[i-1], chars[i]);
            if(pre == State.NORMAL && state != State.NORMAL)
                sb.deleteCharAt(sb.length()-1);
            if(pre == State.NORMAL && state == State.NORMAL) sb.append(chars[i]);
        }
        return sb.toString();
    }

    public static void main(String[] args) {
        String source="/* //aaa  */   bbb  \n // ccc \n";
        System.out.println(new Solution().solve(source));
    }
}