#53 Maximum Subarray ——Top 100 Liked Questions-蒲公英云

#53 Maximum Subarray ——Top 100 Liked Questions

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

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第一次：居然会想到用动态规划！感觉自己进步了hhhh。思路：定义dp，dp[i]=dp[i-1]+nums[i]，如果和较nums[i]增大了，则对应位置保存，如果减小了，对应位置为nums[i]的值不变，最后返回dp中的最大值

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class Solution(object):
    def maxSubArray(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        if not nums:
            return None
        L = len(nums)
        dp = [0] * L
        dp[0] = nums[0]
        for i in range(1, L):
            if nums[i] + dp[i - 1] > nums[i]:
                dp[i] = nums[i] + dp[i - 1]
            else:
                dp[i] = nums[i]
        return max(dp)
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Runtime: 48 ms, faster than 57.44% of Python online submissions for Maximum Subarray.

Memory Usage: 12.7 MB, less than 10.39% of Python online submissions for Maximum Subarray.

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