首页 > itarticle > 238. product of array except self

238. product of array except self

admin 11月 13, 2020 0

explanation

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.)

go through the array from begin to end
go through the array from end to begin

code

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

    }
}