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