題解 | #二叉樹遍歷#
二叉樹遍歷
http://fangfengwang8.cn/practice/4b91205483694f449f94c179883c1fef
s = input()
stack = []#棧實現(xiàn)中序輸出 ps：若是隊列，則是中序
ans = []
for x in s:
if x != "#":
stack.append(x)
else:
if stack:
ans.append(stack.pop())
h = " ".join(ans) + " "
print(h)
