[leetcode]Candy @ Python

原题地址：https://oj.leetcode.com/problems/candy/

题意：

There are N children standing in a line. Each child is assigned a rating value.

You are giving candies to these children subjected to the following requirements:

• Each child must have at least one candy.
• Children with a higher rating get more candies than their neighbors.

What is the minimum candies you must give?

解题思路：求最吝啬的糖果分发数。先从前到后扫描一遍数组，如果序列递增，就+1；然后从后到前扫描一遍数组，序列递增，+1。保证最低谷（ratings最小）永远是1就可以了。

代码: 时间复杂度O(n)，空间复杂度O(n)

class Solution:
    # @param ratings, a list of integer
    # @return an integer
    def candy(self, ratings):
        candyNum = [1] * len(ratings)
        for i in range(1, len(ratings)):
            if ratings[i - 1] < ratings[i]:
                candyNum[i] = candyNum[i - 1] + 1
        for i in range(len(ratings) - 2, -1, -1):
            if ratings[i] > ratings[i + 1] and candyNum[i] <= candyNum[i + 1]:
                candyNum[i] = candyNum[i + 1] + 1
        return sum(candyNum)