# 0632. Smallest Range Covering Elements from K Lists

<https://leetcode.com/problems/smallest-range-covering-elements-from-k-lists>

## Description

You have `k` lists of sorted integers in **non-decreasing order**. Find the **smallest** range that includes at least one number from each of the `k` lists.

We define the range `[a, b]` is smaller than range `[c, d]` if `b - a < d - c` **or** `a < c` if `b - a == d - c`.

**Example 1:**

```
**Input:** nums = [[4,10,15,24,26],[0,9,12,20],[5,18,22,30]]
**Output:** [20,24]
**Explanation:** 
List 1: [4, 10, 15, 24,26], 24 is in range [20,24].
List 2: [0, 9, 12, 20], 20 is in range [20,24].
List 3: [5, 18, 22, 30], 22 is in range [20,24].
```

**Example 2:**

```
**Input:** nums = [[1,2,3],[1,2,3],[1,2,3]]
**Output:** [1,1]
```

**Example 3:**

```
**Input:** nums = [[10,10],[11,11]]
**Output:** [10,11]
```

**Example 4:**

```
**Input:** nums = [[10],[11]]
**Output:** [10,11]
```

**Example 5:**

```
**Input:** nums = [[1],[2],[3],[4],[5],[6],[7]]
**Output:** [1,7]
```

**Constraints:**

* `nums.length == k`
* `1 <= k <= 3500`
* `1 <= nums[i].length <= 50`
* `-105 <= nums[i][j] <= 105`
* `nums[i]` is sorted in **non-decreasing** order.

## ac

```java
```