56. Merge Intervals

Problem Link

Description

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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.

 

Example 1:

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].

Example 2:

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

 

Constraints:

• 1 <= intervals.length <= 104
• intervals[i].length == 2
• 0 <= starti <= endi <= 104

Solution

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Python3

class Solution:
    def merge(self, intervals: List[List[int]]) -> List[List[int]]:
        intervals.sort()
        N = len(intervals)
        res = []
        sx, sy = intervals[0]
 
        for i in range(1, N):
            x, y = intervals[i]
 
            if x > sy:
                res.append([sx, sy])
                sx, sy = x, y
            else:
                sx, sy = min(sx, x), max(sy, y)
        
        res.append([sx, sy])
        return res