'''
给定一个整数数组 nums ，找到一个具有最大和的连续子数组（子数组最少包含一个元素），返回其最大和。
示例：输入：[-2,1,-3,4,-1,2,1,-5,4] 输出：6 解释：连续子数组 [4,-1,2,1] 的和最大，为 6。
'''

class Solution(object):
    def _maxSubArray(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        if len(nums) == 0:
            return 0
        preSum = maxSum = nums[0]
        for i in xrange(1,len(nums)):
            preSum = max(preSum + nums[i],nums[i])
            maxSum = max(maxSum,preSum)
        return maxSum

    def maxSubArray(self, nums):
        if len(nums) == 0:
            return 0
        preSum = maxSum = nums[0]
        for i in xrange(1,len(nums)):
            preSum = (preSum+nums[i] if preSum>0 else nums[i])  # 类似三目运算符
            maxSum = max(maxSum,preSum)
        return maxSum 
    
    def maxSubArray(self, nums):
        for i in range(1, len(nums)):
            nums[i]= nums[i] + max(nums[i-1], 0)
        return max(nums)