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]
2 <= nums.length <= 10^5-30 <= nums[i] <= 30Use a prefix product array and a suffix product — combine them.
public int[] productExceptSelf(int[] nums) {
int n = nums.length;
int[] result = new int[n];
// Build prefix products into result
result[0] = 1;
for (int i = 1; i < n; i++) {
result[i] = result[i - 1] * nums[i - 1];
}
// Multiply suffix products from right
int suffix = 1;
for (int i = n - 1; i >= 0; i--) {
result[i] *= suffix;
suffix *= nums[i];
}
return result;
}Time: O(n) · Space: O(1)