- Maximum Product Subarray Medium
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Share Given an integer array nums, find the contiguous subarray within an array (containing at least one number) which has the largest product.
Example 1:
Input: [2,3,-2,4] Output: 6 Explanation: [2,3] has the largest product 6. Example 2:
Input: [-2,0,-1] Output: 0 Explanation: The result cannot be 2, because [-2,-1] is not a subarray. Accepted
思路：因为有负数存在，所以必须存 imax，imin for循环数组 1.nums[i]为正时，imax=max(imaxnums[i],nums[i]) imin=min(iminnums[i],nums[i]) 2.nums[i]为负时，临时变量tm=imax先存一下 imax=max(iminnums[i],nums[i]) imin=min(tmnums[i],nums[i]) res=max(res,imax)
代码：python3
class Solution:
def maxProduct(self, nums: List[int]) -> int:
imax=nums[0]
imin=nums[0]
res=nums[0]
for i in range(1,len(nums)):
if nums[i]>0:
imax=max(imax*nums[i],nums[i])
imin=min(imin*nums[i],nums[i])
else:
t=imax
imax=max(imin*nums[i],nums[i])
imin=min(t*nums[i],nums[i])
res=max(res,imax)
return res
时间复杂度：O(m) 空间复杂度：O(1)
