python 动态规划题------求最大连续子串和

def maxSubArray(nums):
	'''
	求最大子串和

	'''
	# print(len(nums))
	# 如果该串长度为一,和最大的子串就是本身
	if len(nums)==1:
		return nums[0]

	# 用来存放每次更新的最大子串和
	max_ret = nums[0]
	cur_max = last_max = nums[0]

	# 状态转移方程,一步步的分解子问题
	for i in range(1,len(nums)):
		if last_max+nums[i] < nums[i]:
			cur_max = nums[i]
		else:
			cur_max = last_max+nums[i]
		if cur_max > max_ret:
			max_ret = cur_max
		last_max = cur_max
	return max_ret
list01=[2,-5,-6,-8,-3,3,56,6,3,6,7,100,9,3]
# list01=[1,2,3,-1]
print(maxSubArray(nums=list01))
# 算法复杂度为O(N),(需要循环遍历整个串)