出栈顺序实现

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]