题解 | 吐泡泡

import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        while(n-->0){
        String s = in.next();
        Deque<Character> stack = new ArrayDeque<>();
        for (int i = 0; i < s.length(); i++) {
            char c = s.charAt(i);//要加入的泡泡
            if (!stack.isEmpty()) {
                char before = stack.peek();//当前的泡泡
                if (before == 'o' && c == 'o') {
                    stack.pop();
                    //变成O stack.peek()上一个泡泡=='O'
                    if(!stack.isEmpty() && stack.peek() == 'O') {
                        stack.pop();
                    }//解决Oo o问题
                    else stack.push('O');
                    continue;
                }
                if (before == 'O' && c == before) {
                    stack.pop();
                    continue;
                }
            }
            stack.push(c);
        }
        StringBuilder sb = new StringBuilder();
        int len = stack.size();
        for (int i = 0; i < len; i++) {
            sb.append(stack.pop());
        }
        System.out.println(sb.reverse());
        }
    }
}