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56. Merge Intervals

Array Sorting

Problem - Merge Intervals

Medium

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.

Example 3:

Input: intervals = [[4,7],[1,4]]
Output: [[1,7]]
Explanation: Intervals [1,4] and [4,7] are considered overlapping.

 

Constraints:

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

Solutions

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class Solution:
    def merge(self, intervals: List[List[int]]) -> List[List[int]]:
        intervals.sort()
        result = [intervals[0]]

        for left, right in intervals:
            if result[-1][1] < left: # No overlap, this interval's left is more then the last one's right(no overlap) 
                result.append([left, right])
            else:
                result[-1][1] = max(result[-1][1], right) # Overlap, the max of the last interval's right and the 
        return result                                     #  current right is the new interval's right

Submission Stats:

  • Runtime: 7 ms (73.08%)
  • Memory: 21.7 MB (15.72%)