题解 | #牛群的最大能量环#

key：

• 既然是环，那就手动补成一个环
• 注意“补丁1”：当r不能移动时，如何移动l有两种情况：l != r、 l < r

class Solution:
    def maxEnergyCircular(self , energy: List[int]) -> int:
        lenth = len(energy)
        if lenth == 1:
            return energy[0]

        energy = energy + energy[:-1]

        result = energy[0]
        l, r = 0, 0
        tmp = energy[0]
        
        while r < len(energy):
            if r - l + 1 == lenth:
                tmp -= energy[l]
                l += 1
                result = max(result, tmp)
                continue

            if r < len(energy) - 1 and tmp + energy[r + 1] >= 0:
                r += 1
                tmp += energy[r]
                result = max(result, tmp)

            else:
                if l < r:
                    while l < r:
                        tmp -= energy[l]
                        l += 1
                        result = max(result, tmp)
                
                # 补丁1：当r不能移动时，如何移动l有两种情况：l != r时， l < r时。
                else:
                    r += 1
                    l += 1
                    tmp = energy[r]
                    result = max(result, tmp)

            if l == len(energy) - 1 and r == len(energy) - 1:
                return result