# Past Challenges

## 26. Merge Intervals

Write a function `solve` that merges overlapping intervals and returns the merged list. Intervals are represented as lists of two integers: start and end.

**Example:**
`Input: [[1,3],[2,6],[8,10],[15,18]]`

`Output: [[1,6],[8,10],[15,18]]`

Make sure you `return` your solution, don't print!

```python

def solve(intervals):
    pass
```