238. Product of Array Except Self java solutions

Given an array of n integers where n > 1, nums, return an array output such that output[i] is equal to the product of all the elements of nums except nums[i].

Solve it without division and in O(n).

For example, given [1,2,3,4], return [24,12,8,6].

Follow up:
Could you solve it with constant space complexity? (Note: The output array does not count as extra space for the purpose of space complexity analysis.)

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public class Solution {
    public int[] productExceptSelf(int[] nums) {
        int[] ans = new int[nums.length];
        for(int i = 0,tmp = 1;i < nums.length; i++){
            ans[i] = tmp;
            tmp *= nums[i];
        }
        for(int i = nums.length - 1,tmp = 1;i >= 0; i--){
            ans[i] *= tmp;
            tmp *= nums[i];
        }
        return ans;
    }
}

从左往右遍历一次，再从右往左遍历一次，即可得答案。