[LC] 238. Product of Array Except Self


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

Example:

Input:  [1,2,3,4]
Output: [24,12,8,6]

Note: Please solve it without division and in O(n).

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

class Solution {
    public int[] productExceptSelf(int[] nums) {
        if (nums == null || nums.length == 0) {
            return nums;
        }
        int[] resArr = new int[nums.length];
        resArr[0] = 1;
        for (int i = 1; i < nums.length; i++) {
            resArr[i] = resArr[i - 1] * nums[i - 1];
        }
        
        int right = 1;
        for (int i = nums.length - 1; i >= 0; i--) {
            resArr[i] *= right;
            right *= nums[i];
        }
        return resArr;
    }
}

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转载自www.cnblogs.com/xuanlu/p/11881034.html
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