利用动态规划的思想,最大子链表的和只与之前子链表+当前值 和 当前值有关,并用一个全局值记录整个过程中出现的最大值

# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None
#
# 代码中的类名、方法名、参数名已经指定,请勿修改,直接返回方法规定的值即可
#
# 
# @param head ListNode类 
# @return int整型
#
class Solution:
    def FindGreatestSumOfSubArray(self , head: ListNode) -> int:
        # write code here
        if not head: return 0
        if not head.next:return head.val
        res = cur = float("-inf")
        while head:
            cur = max(cur + head.val, head.val)
            res = max(res, cur)
            head = head.next
        return res