题解 | 吐泡泡

class Stack:
    def __init__(self) -> None:
        self.items = []

    def push(self, x):
        self.items.append(x)

    def pop(self):
        if not self.is_empty():
            self.items.pop()

    def is_empty(self):
        return len(self.items) == 0

    def peek(self):  # 修正拼写
        if not self.is_empty():
            return self.items[-1]
        return None

def tu_bubbles(bubbles):
    # 初始化栈
    stack = Stack()
    # 遍历泡泡序列
    for bubble in bubbles:
        if bubble == "o":
            if stack.peek() == "o":
                stack.pop()
                if stack.peek() == "O":
                    stack.pop()
                else:
                    stack.push("O")
            else:
                stack.push("o")
        elif bubble == "O":
            if stack.peek() == "O":
                stack.pop()
            else:
                stack.push("O")
    # 输出最终结果
    return "".join(stack.items)

# 读取输入
import sys
n = int(input())
for line in sys.stdin:
    s = line.strip()
    print(tu_bubbles(s))