题目描述

blablabla

算法1

(暴力枚举) $O(n^2)$

blablabla

时间复杂度

参考文献

Python 代码

import sys
n = int(input())

res = []
stack = [0] * (n+1)



def dfs(top, x):
    global cnt 
    if cnt >= 20: return 
    if x > n and top == 0:  # 全部出栈 栈中无元素
        tmp = ""
        for i in range(n):
            tmp += str(res[i])
        cnt += 1
        print(tmp)

        return 
    if top:
        cur = stack[top]
        res.append(cur)
        dfs(top - 1, x)   # 出栈
        res.pop()
        stack[top] = cur



    if x <= n:
        stack[top + 1] = x
        dfs(top + 1, x + 1)  #x 进栈
if __name__ == "__main__":
    cnt = 0
    dfs(0,1)