# 1215. Stepping Numbers

<https://leetcode.com/problems/stepping-numbers>

## Description

A **stepping number** is an integer such that all of its adjacent digits have an absolute difference of exactly `1`.

* For example, `321` is a **stepping number** while `421` is not.

Given two integers `low` and `high`, return *a sorted list of all the **stepping numbers** in the inclusive range* `[low, high]`.

**Example 1:**

```
**Input:** low = 0, high = 21
**Output:** [0,1,2,3,4,5,6,7,8,9,10,12,21]
```

**Example 2:**

```
**Input:** low = 10, high = 15
**Output:** [10,12]
```

**Constraints:**

* `0 <= low <= high <= 2 * 109`

## ac

```java
```