*Product of Array Except Self

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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.)

public class Solution {
public int[] productExceptSelf(int[] nums) {
    int leng = nums.length;
    int[] ret = new int[leng];
    if(leng == 0)
        return ret;
    int runningprefix = 1;
    for(int i = 0; i < leng; i++){
        ret[i] = runningprefix;
        runningprefix*= nums[i];
    }
    int runningsufix = 1;
    for(int i = leng -1; i >= 0; i--){
        ret[i] *= runningsufix;
        runningsufix *= nums[i];
    }
    return ret;

}

reference：https://leetcode.com/discuss/53781/my-solution-beats-100%25-java-solutions

*Product of Array Except Self

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原文地址：http://www.cnblogs.com/hygeia/p/4859951.html