[Leetcode][Python]56: Merge Intervals

# -*- coding: utf8 -*-‘‘‘__author__ = ‘[email protected]‘

56: Merge Intervalshttps://oj.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].

===Comments by Dabay===这道题想起来比较简单，实现的时候恼火。技巧在与，不是一个个地插入到已有的序列，而是把已有的序列插入到一个标杆Interval前面、交叉、后面。

对于每一个序列中的Interval，    - 如果它的end比标杆的start小，插入到前面    - 如果它的start比标杆的end大，插入到后面    - 如果它和标杆有交集，更新标杆的start和end‘‘‘# Definition for an interval.class Interval:    def __init__(self, s=0, e=0):        self.start = s        self.end = e

class Solution:    # @param intervals, a list of Interval    # @return a list of Interval    def merge(self, intervals):        def insert(interval, merged):            new_merged = []            i = 0            s = interval.start            e = interval.end            while i < len(merged):                if merged[i].end < s:                    new_merged.append(merged[i])                    i = i + 1                    continue                if e < merged[i].start:                    new_merged = new_merged + [Interval(s, e)] + merged[i:]                    break                s = min(s, merged[i].start)                e = max(e, merged[i].end)                i = i + 1            else:                new_merged.append(Interval(s, e))            return new_merged

        if len(intervals) <= 1:            return intervals

        merged = [intervals[0]]        i = 1        while i < len(intervals):            merged = insert(intervals[i], merged)            i = i + 1

        return merged

def main():    sol = Solution()    i1 = Interval(2,3)    i2 = Interval(4,5)    i3 = Interval(2,2)    i4 = Interval(15,18)    intervals = [i1,i2,i3,i4]    intervals = sol.merge(intervals)    for interval in intervals:        print "[%s, %s] " % (interval.start, interval.end),    print

if __name__ == "__main__":    import time    start = time.clock()    main()    print "%s sec" % (time.clock() - start)