贪心_leetcode435

#coding=utf-8

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

def compare1(x, y):
    if x.start < y.start:
        return -1
    elif x.start > y.start:
        return 1
    else:
        if x.end < y.end:
            return -1
        elif x.end > y.end:
            return 1
        else:
            return 0
# 动态规划
# 最长上升子序列
class Solution1(object):
    def eraseOverlapIntervals(self, intervals):
        """
        :type intervals: List[Interval]
        :rtype: int
        """

        if not intervals:
            return 0

        intervals.sort(key=lambda x:(x.start,x.end))

        memo = [1 for i in range(len(intervals))]


        for i in range(1,len(intervals)):
            for j in range(i):
                if intervals[i].start >= intervals[j].end:
                    memo[i] = max(memo[i],memo[j]+1)


        res = 0
        for i in range(len(memo)):
            res = max(res,memo[i])

        return len(intervals) - res

# 贪心
class Solution2(object):
    def eraseOverlapIntervals(self, intervals):
        """
        :type intervals: List[Interval]
        :rtype: int
        """
        if not intervals:
            return 0

        intervals.sort(key=lambda x: (x.end, x.start))

        res = 1

        pre = 0

        for i in range(1,len(intervals)):
            if intervals[i].start >= intervals[pre].end:
                res += 1
                pre = i



        return len(intervals) - res