merge-intervals.py

# -*- coding:utf-8 -*-


# 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.
#


# Definition for an interval.
# class Interval(object):
#     def __init__(self, s=0, e=0):
#         self.start = s
#         self.end = e

class Solution(object):
    def merge(self, intervals):
        """
        :type intervals: List[Interval]
        :rtype: List[Interval]
        """
        if not intervals:
            return []
        
        intervals.sort(key = lambda x: x.start, reverse=True)
        stack = []
        tmp = intervals.pop()
        while intervals:
            x = intervals.pop()
            if tmp.end >= x.start:
                tmp.end = max(tmp.end, x.end)
            else:
                stack.append(tmp)
                tmp = x
        stack.append(tmp)
        return stack