Find the Narrowest Interval Meeting Every Sorted List
Company: Amazon
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: hard
Interview Round: Other
### Problem
Return [a,b] containing at least one element from every sorted list in nums. Minimize b-a, breaking equal-width ties by the smaller a. Endpoints are inclusive.
```cpp
class Solution {
public:
vector<int> smallestRange(vector<vector<int>>& nums);
};
```
### Examples
**Example 1:**
```text
nums = [[1,6],[3,8],[4,7]]
Output: [6,8]
Explanation: 6,8,7 cover all lists in width two.
```
**Example 2:**
```text
nums = [[0,5],[1,6]]
Output: [0,1]
Explanation: [5,6] has equal width but a larger left endpoint.
```
### Constraints
- There are k=nums.length lists, with k in 1..3500. Each has 1..50 entries in nondecreasing order. Values range from -100000 through 100000.
### Clarifying Questions
Cover every list, keep the running maximum synchronized and apply the explicit left-endpoint tie-break.
```hint Read the boundary condition
Which current list value must change before an interval can become narrower?
```
### Contract considerations
Cover every list, keep the running maximum synchronized and apply the explicit left-endpoint tie-break.
Overview: Find the Narrowest Interval Meeting Every Sorted List. Return [a,b] containing at least one element from every sorted list in nums.
