Never take some guess for granted!

[1, 2, 2] is not 5, should be 4!

Useq/Dseq stores one should have ?+1 candies since he/her has higher rating than left/right neighbor!

```
class Solution:
# @param {integer[]} ratings
# @return {integer}
def candy(self, ratings):
n = len(ratings)
Useq = [0 for i in range(n)]
for i in xrange(1, n):
if ratings[i]>ratings[i-1]:
Useq[i] = Useq[i-1]+1
Dseq = [0 for i in range(n)]
for i in xrange(n-2, -1, -1): #from i = n-2, ... 1, 0 ## will not reach -1!!
if ratings[i]>ratings[i+1]:
Dseq[i] = Dseq[i+1]+1
candies = [max(Useq[i], Dseq[i])+1 for i in range(n)]
return sum(candies)
```