leetcode 238. Product of Array Except Self

题目

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.)

解

public class Solution {
     public int[] productExceptSelf(int[] nums) {
         int len=nums.length;
         int[] ret=new int[len];

         int[] rightArr=new int[len];
         int[] leftArr=new int[len];

         leftArr[0]=1;
         int left=1;
         for(int i=1;i1]*left;
             left=leftArr[i];
         }

//       String b1=Arrays.toString(leftArr);
//       System.out.println(b1);

         rightArr[len-1]=1;
         int right=1;
         for(int j=len-2;j>=0;j--){
             rightArr[j]=nums[j+1]*right;
             right=rightArr[j];
         }

//       String b2=Arrays.toString(rightArr);
//       System.out.println(b2);
//   

         for(int i=0;ireturn ret;            
     }
}