solved 'Candies' on hackerrank https://www.hackerrank.com/challenges/candies

candies.py

import sys

def find_min_candies(ratings):
  """ratings: A list of ratings"""
  sz = len(ratings)
  
  # Records number of continuous elements less than
  # the current rating from left and right.
  less_from_left, less_from_right = [0] * sz, [0] * sz
  for i in range(1, sz):
    if ratings[i - 1] < ratings[i]:
      less_from_left[i] = less_from_left[i - 1] + 1
    if ratings[-i] < ratings[-i - 1]:
      less_from_right[-i - 1] = less_from_right[-i] + 1
  
  # The number of candies is bounded by the greater of 
  # the corresponding element in above arrays.
  min_candies = sum(
      max(pair) + 1 for pair in zip(less_from_left, less_from_right))
  return min_candies
  

if __name__ == '__main__':
  raw_input()
  ratings = map(int, sys.stdin.readlines())
  print find_min_candies(ratings)