LeetCode 238

Product of Array Except Self

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.)

 /*************************************************************************
     > File Name: LeetCode238.c
     > Author: Juntaran
     > Mail: Jacinthmail@gmail.com
     > Created Time: 2016年04月28日 星期四 23时40分01秒
  ************************************************************************/

 /*************************************************************************

     Product of Array Except Self

     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.)

  ************************************************************************/

 #include<stdio.h>

 /**
  * Return an array of size *returnSize.
  * Note: The returned array must be malloced, assume caller calls free().
  */
 int* productExceptSelf(int* nums, int numsSize, int* returnSize)
 {
     if( numsSize ==  )
     {
         return ;
     }

     int *result = malloc(numsSize*sizeof(int));
     *returnSize = numsSize;

     /* 从左往右 */
     int i;
     int leftProduct = ;
     int rightProduct = ;

     for( i=; i<numsSize; i++ ){
         result[i] = leftProduct;
         leftProduct *= nums[i];
     }
     /* 从右往左 */
     for( i = numsSize - ; i>=; i-- ){
         result[i] *= rightProduct;
         rightProduct *= nums[i];
     }

     return result;
 }

 int main(){

     int nums[] = {,,,,,,};
     int numsSize = ;
     int returnSize[numsSize];
     productExceptSelf( nums, numsSize, returnSize);
     return ;
 }