135. 分发糖果

题目链接	135. 分发糖果
思路	动态规划
题解链接	动态规划，计算最长递减序列
关键点	识别出：发放的糖果的数量实质上需要找到“最长递增子串”的长度
时间复杂度	\(O(n)\)
空间复杂度	\(O(n)\)

代码实现：

class Solution:
    def candy(self, ratings: List[int]) -> int:
        n = len(ratings)

        dp_left = [1] * n
        dp_right = [1] * n

        for i in range(1, n):
            if ratings[i] > ratings[i-1]:
                dp_left[i] = dp_left[i-1] + 1
            else:
                dp_left[i] = 1
            
            if ratings[n-1-i] > ratings[n-i]:
                dp_right[n-1-i] = dp_right[n-i] + 1
            else:
                dp_right[n-1-i] = 1
            
        answer = sum(max(left, right) for left, right in zip(dp_left, dp_right))
        return answer