> ## Documentation Index
> Fetch the complete documentation index at: https://leetcode-py.wisl.dev/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> leetcode-py is a Python LeetCode practice environment generator with one CLI: lcpy. It is not a service or platform.
> Each problem is a directory under leetcode/ with README.md, solution.py, test_solution.py, helpers.py, and playground.ipynb. lcpy gen creates them from JSON templates bundled with the package.
> Examples are backed by tests; copy them verbatim.

# Merge Intervals Python Solution with Tests

> Tested Python solution for LeetCode 56 with 12 pytest cases. Generate a practice environment with lcpy.

LeetCode 56, Medium. Topics: Array, Sorting. [View on LeetCode](https://leetcode.com/problems/merge-intervals/description/).

Generate this problem as a practice environment: tested reference solution, 12 [parametrized pytest cases](/practice/testing), and a playground notebook:

```bash theme={"theme":{"light":"github-light","dark":"github-dark"}}
lcpy gen -n 56   # by problem number
lcpy gen -s merge_intervals   # by problem name
```

## Problem

Given an array of `intervals` where `intervals[i] = [starti, endi]`, merge all overlapping intervals, and return an array of the non-overlapping intervals that cover all the intervals in the input.

### Examples

```
Input: intervals = [[1,3],[2,6],[8,10],[15,18]]
Output: [[1,6],[8,10],[15,18]]
```

**Explanation:** Since intervals \[1,3] and \[2,6] overlap, merge them into \[1,6].

```
Input: intervals = [[1,4],[4,5]]
Output: [[1,5]]
```

**Explanation:** Intervals \[1,4] and \[4,5] are considered overlapping.

```
Input: intervals = [[4,7],[1,4]]
Output: [[1,7]]
```

**Explanation:** Intervals \[1,4] and \[4,7] are considered overlapping.

### Constraints

* `1 <= intervals.length <= 10^4`
* `intervals[i].length == 2`
* `0 <= starti <= endi <= 10^4`

## Solution

Reference implementation from [solution.py on GitHub](https://github.com/wislertt/leetcode-py/blob/main/leetcode/merge_intervals/solution.py), full suite in [test\_solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/merge_intervals/test_solution.py):

```python theme={"theme":{"light":"github-light","dark":"github-dark"}}
class Solution:
    # Time: O(n log n)
    # Space: O(1)
    def merge(self, intervals: list[list[int]]) -> list[list[int]]:
        intervals.sort()
        merged = [intervals[0]]

        for start, end in intervals[1:]:
            if start <= merged[-1][1]:
                merged[-1][1] = max(merged[-1][1], end)
            else:
                merged.append([start, end])

        return merged
```

## Complexity

| Time       | Space |
| ---------- | ----- |
| O(n log n) | O(1)  |

## Tags

[Grind 75](/catalog/grind-75), [Grind](/catalog/grind), [Blind 75](/catalog/blind-75), [NeetCode 150](/catalog/neetcode-150), [NeetCode 250](/catalog/neetcode-250), [NeetCode All](/catalog/neetcode), [AlgoMaster 75](/catalog/algo-master-75).