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] <= 30nums is 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.)
class Solution {
public int[] productExceptSelf(int[] nums) {
int n = nums.length, prefix = 1, suffix = 1;
int[] ans = new int[n];
Arrays.fill(ans, 1);
for (int i = 0; i < n; i++) {
ans[i] *= prefix;
ans[n - 1 - i] *= suffix;
prefix *= nums[i];
suffix *= nums[n - 1 - i];
}
return ans;
}
}