0056: Merge Intervals

Problem Statement

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

Code Solution

class Solution:
    def merge(self, intervals):
	    
        intervals.sort(key=lambda x: (x[0], x[1]))
        prev = intervals[0]
        
        out = [prev]
        for ix in range(1, len(intervals)):
            curr = intervals[ix]
            if prev[1] >= curr[0]:
                prev[1] = max(prev[1], curr[1])
                continue
            out.append(curr)
            prev = curr
        
        return out