135. 分发糖果

https://leetcode-cn.com/problems/candy/
从前往后遍历，每次和前面一个元素比。
从后往前遍历，每次和后面一个元素比

  1. class Solution:
  2.     def candy(self, ratings: List[int]) -> int:
  3.         res = [1]*len(ratings)
  5.         for i in range(1,len(ratings)):
  6.             if ratings[i] > ratings[i-1]:
  7.                 res[i]=res[i-1] + 1
  8.         for i in range(len(ratings)-2,-1,-1):
  9.             if ratings[i] > ratings[i+1] and res[i]<=res[i+1]:
  10.                 res[i]=res[i+1] + 1
  11.         return sum(res)

435. 无重叠区间

https://leetcode-cn.com/problems/non-overlapping-intervals/
这道题说的是算出需要移除区间的最少数量，那我们就要尽可能的把右边界小的区间留下来，如果区间交叉了，不更新边界，因为是用右边界排序的， 如果没有交叉，那更新目前无重叠区间的右边界

  1. class Solution:
  2.     def eraseOverlapIntervals(self, intervals: List[List[int]]) -> int:
  3.         if len(intervals) < 2:
  4.             return 0
  5.         count = 0
  6.         intervals = sorted(intervals, key = lambda a:a[1])
  7.         end = intervals[0][1]
  8.         for s,e in intervals[1:]:
  9.             if s < end:
  10.                 count+=1
  11.             else:
  12.                 end = e
  13.         return count