[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