LeetCode-in-All
238. Product of Array Except Self
Medium
Given an integer array nums, return an array answer such that answer[i] is equal to the product of all the elements of nums except nums[i].
The product of any prefix or suffix of nums is guaranteed to fit in a 32-bit integer.
You must write an algorithm that runs in O(n) time and without using the division operation.
Example 1:
Input: nums = [1,2,3,4]
Output: [24,12,8,6]
Example 2:
Input: nums = [-1,1,0,-3,3]
Output: [0,0,9,0,0]
Constraints:
2 <= nums.length <= 105-30 <= nums[i] <= 30- The product of any prefix or suffix of
numsis guaranteed to fit in a 32-bit integer.
Follow up: Can you solve the problem in O(1) extra space complexity? (The output array does not count as extra space for space complexity analysis.)
Solution
func productExceptSelf(nums []int) []int {
n := len(nums)
product := 1
ans := make([]int, n)
// Calculate the product of all elements in the array
for _, num := range nums {
product *= num
}
// Calculate the result array
for i := 0; i < n; i++ {
if nums[i] != 0 {
ans[i] = product / nums[i]
} else {
p := 1
for j := 0; j < n; j++ {
if j != i {
p *= nums[j]
}
}
ans[i] = p
}
}
return ans
}