給定乙個由n個整數組成的陣列，其中n> 1，則返回乙個陣列輸出，使得output [i]等於除nums [i]之外的所有nums元素的乘積。
example:
input: [1,2,3,4]
output: [24,12,8,6]
class
solution
:def
productexceptself
(self, nums: list[
int])-
> list[
int]
: output =[0
]*len(nums)
for i in
range
(len
(nums)):
output[i]
= self.helper(nums,
0,i)
* self.helper(nums,i +1,
len(nums)
)return output
defhelper
(self,nums,start,end)
:if start >= end:
return
1 result =
1for i in
range
(start,end)
: result = result * nums[i]
return result
通過兩個陣列分別儲存當前元素的前面元素乘積，和後面元素的乘積，然後兩個乘積即可。通過三次遍歷，前後前。
class
solution
:def
productexceptself
(self, nums: list[
int])-
> list[
int]
: left =[0
]*len(nums)
right =[0
]*len(nums)
left[0]
=1right[
len(nums)-1
]=1for i in
range(1
,len
(nums)):
left[i]
= nums[i-1]
* left[i -1]
print
(right)
for i in
range
(len
(nums)-2
,-1,
-1):
right[i]
= right[i +1]
* nums[i +1]
result =[0
]*len(nums)
for i in
range
(len
(nums)):
result[i]
= left[i]
*right[i]
return result
class
solution
:def
productexceptself
(self, nums: list[
int])-
> list[
int]
: result,right =[1
]*len(nums),1
for i in
range(1
,len
(nums)):
result[i]
= nums[i-1]
* result[i -1]
for i in
range
(len
(nums)-1
,-1,
-1):
result[i]
= right * result[i]
right *= nums[i]
return result
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