题解 | 吐泡泡

t = int(input())
for _ in range(t):
    s = input()
    stack = []#定义初始化空栈
    for c in s:
        if len(stack)>0 and c=='O' and stack[-1]=='O':
            stack.pop()#两个大写O。出栈栈尾的大写O，消除
        elif len(stack)>1 and c=='o' and stack[-1]=='o' and stack[-2]=='O':
            del(stack[-2:])#一个大写O，两个小写o。出栈栈尾的大写O和小写o，消除
        elif len(stack)>0 and c=='o' and stack[-1]=='o':
            stack.pop()#只有两个小写o，栈尾出栈一个小写o，合成一个大写O并入栈尾
            stack += ['O']
        else:#其余情况，直接入栈尾
            stack += [c]
    print(''.join(stack))