1. 统计元素出栈可能的顺序
res = []
def dfs(wait, stack, out):
if not wait and not stack:
res.append( out)
if wait: # 入栈
dfs(wait[1:], stack + [wait[0]], out)
if stack: # 出栈
dfs(wait, stack[:-1], out + [stack[-1]])
#元素进栈顺序
nums = [1, 2, 3]
dfs(nums, [], [])
print("打印所有出栈可能的顺序")
for data in res:
print(data)
输出结果为：
打印所有出栈可能的顺序
[3, 2, 1]
[2, 3, 1]
[2, 1, 3]
[1, 3, 2]
[1, 2, 3]