# LeetCode 56. Merge Intervals

## Description

https://leetcode.com/problems/merge-intervals/

Given a collection of intervals, merge all overlapping intervals.

Example 1:

```Input: [[1,3],[2,6],[8,10],[15,18]]
Output: [[1,6],[8,10],[15,18]]
Explanation: Since intervals [1,3] and [2,6] overlaps, merge them into [1,6].
```

Example 2:

```Input: [[1,4],[4,5]]
Output: [[1,5]]
Explanation: Intervals [1,4] and [4,5] are considered overlapping.```

NOTE: input types have been changed on April 15, 2019. Please reset to default code definition to get new method signature.

## Explanation

base on start and end to merge interval

## Python Solution

``````class Solution:
def merge(self, intervals: List[List[int]]) -> List[List[int]]:
result = []

intervals = sorted(intervals, key=lambda interval:interval[0])

for interval in intervals:
if len(result) == 0 or result[-1][1] < interval[0]:
result.append(interval)
else:
result[-1][1] = max(result[-1][1], interval[1])

return result``````
• Time complexity: ~ N
• Space complexity: ~1