Maximum Subarray

题目

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.

解决方案

class Solution:
    def maxSubArray(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        cs,s,e,cn,ma = 0,0,1,nums[0],nums[0]
        for i in range(len(nums)):
            if i == 0:continue
            if nums[i] + cn >= nums[i]:
                cn = cn + nums[i]
            else:
                cn = nums[i]
                cs = i
            if ma > cn:
                pass
            else:
                ma  = cn
                s = cs
                e  = i + 1
        # print(s,e,ma,nums[s:e])
        return ma
        

算法思想

主要是考虑贪心算法，本题是求解最长连续子段和，使用的就是贪心，如果前面的加当前的是正的我们就认为他是有益的,否则就是有害的,从当前开始算

复杂度分析

时间复杂度 主要是 用了一个一维的循环 时间复杂度在 O(n)