53. Maximum Subarray@python

Given an integer array nums, find the contiguous subarray (containing at least one number) which has the largest sum and return its sum.

Example:

Input: [-2,1,-3,4,-1,2,1,-5,4],
Output: 6
Explanation: [4,-1,2,1] has the largest sum = 6.

Follow up:

If you have figured out the O(n) solution, try coding another solution using the divide and conquer approach, which is more subtle.

題目地址:  Maximum Subarray 

難度: Easy

思路: 最大子序列和問題

代碼:

class Solution(object):
    def maxSubArray(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        n = len(nums)
        tmp = 0
        res = float('-inf')
        for i in range(n):
            if tmp < 0:
                tmp = 0
            tmp = tmp + nums[i]
            res = max(res, tmp)
        return res

時間複雜度: O(n)

空間複雜度: O(1)