[LeetCode]题解（python）：056-Merge Intervals

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题目来源

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

Given a collection of intervals, merge all overlapping intervals.

For example,
Given [1,3],[2,6],[8,10],[15,18],
return [1,6],[8,10],[15,18].

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题意分析

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Input:a list of intervals

Output:a list of intervals but merged

Conditions:如果两个interval有重叠，则合并

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题目思路

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首先对所有的intervals按照start排序，然后如果后一个interval的start在前一个interval之中，那么合并这两个interval；如果不在，则把新的interval加入

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AC代码（Python）

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 # 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]
         """
         intervals.sort(key = lambda x:x.start)
         length = len(intervals)
         res = []
         if length == 0:
             return res
         res.append(intervals[0])
         for i in range(1,length):
             size = len(res)
             if res[size - 1].start <= intervals[i].start <= res[size - 1].end:
                 res[size - 1].end = max(intervals[i].end, res[size - 1].end)
             else:
                 res.append(intervals[i])

         return res