LeetCode [135] Candy

Note:

• step 1: give each child one candy regardless of his/her rating
• step 2: forward, if i-th child has higher rating than (i-1)-th child, candies[i] should be greater than candies[i-1]
• step 3: backward, if i-th child has higher rating than (i+1)-th child, candies[i] should be greater candies[i+1]
• return sum of candies

Ref

[1] https://leetcode.com/problems/candy/

OJ
[2] https://leetcode.com/discuss/23835/one-pass-constant-space-java-solution
One pass, O(1) space