leetcode - 556. Next Greater Element III

Description

Given a positive integer n, find the smallest integer which has exactly the same digits existing in the integer n and is greater in value than n. If no such positive integer exists, return -1.

Note that the returned integer should fit in 32-bit integer, if there is a valid answer but it does not fit in 32-bit integer, return -1.

Example 1:

复制代码
Input: n = 12
Output: 21

Example 2:

复制代码
Input: n = 21
Output: -1

Constraints:

复制代码
1 <= n <= 2^31 - 1

Solution

Solved after help...

Same as 31. 下一个排列

The next greater number should be: start from the rightmost, and until we find a digit that is smaller than at least one of the digits we have visited, we should swap the digit with the minimum but larger digit of all the digits we have visited. Then sort all the digits at the right. Then we would get our answer.

Time complexity: o ( n log ⁡ n ) o(n\log n) o(nlogn)

Space complexity: o ( n ) o(n) o(n)

Code

python3 复制代码
class Solution:
    def nextGreaterElement(self, n: int) -> int:
        num_list = []
        while n > 0:
            num_list.append(n % 10)
            n //= 10
        stack = []
        for i in range(len(num_list)):
            if not stack or num_list[stack[-1]] <= num_list[i]:
                stack.append(i)
            else:
                swap_index = stack[-1]
                # swap current number with previous minimum larger one
                while stack and num_list[stack[-1]] > num_list[i]:
                    swap_index = stack.pop()
                num_list[i], num_list[swap_index] = num_list[swap_index], num_list[i]
                num_list[:i] = sorted(num_list[:i], reverse=True)
                i = len(num_list) + 1
                break
        if i == len(num_list) + 1:
            res = eval(''.join(map(str, num_list[::-1])))
            if res > 2 ** 31 - 1:
                res = -1
        else:
            res = -1
        return res
相关推荐
岩中竹1 分钟前
力扣热题100题解(c++)—矩阵
数据结构·c++·程序人生·算法·leetcode·矩阵
啊阿狸不会拉杆4 分钟前
数据结构-图
java·c语言·数据结构·c++·python·算法·图论
SophiaSSSSS2 小时前
无标注文本的行业划分(行业分类)算法 —— 无监督或自监督学习
学习·算法·分类
明月清了个风2 小时前
数据结构与算法学习笔记(Acwing提高课)----动态规划·数字三角形
笔记·学习·算法·动态规划
刃神太酷啦2 小时前
堆和二叉树--数据结构初阶(3)(C/C++)
c语言·数据结构·c++·算法·leetcode·深度优先·宽度优先
●VON2 小时前
杭电oj(1087、1203、1003)题解
算法·leetcode·职场和发展
良木林2 小时前
240424 leetcode exercises II
c语言·数据结构·算法·leetcode
云之兕3 小时前
在面试中被问到spring是什么?
spring·面试·职场和发展
啊阿狸不会拉杆3 小时前
数据结构-排序
java·c语言·数据结构·c++·python·算法·排序算法
姜行运3 小时前
数据结构【树和二叉树】
android·数据结构·算法·c#