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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
object Solution {
def productExceptSelf(nums: Array[Int]): Array[Int] = {
var product = 1
val ans = new Array[Int](nums.length)
for (num <- nums) {
product = product * num
}
for (i <- nums.indices) {
if (nums(i) != 0) {
ans(i) = product / nums(i)
} else {
var p = 1
for (j <- nums.indices) {
if (j != i) {
p = p * nums(j)
}
}
ans(i) = p
}
}
ans
}
}