构建乘积数组 --剑指offer

import java.util.ArrayList;
public class Solution {
    public static int[] multiply(int[] A) {
        long result=1;
        int len=A.length;
        int[] B = new int[len];
        if(len == 0 || A== null){
            return  A;
        }
        B[0] = 1;
        for(int i =1;i < len;i ++){
            B[i] = B[i-1]*A[i-1];
        }
        int tem=1;
        for(int i = len-2;i >=0 ;i --){
            tem *= A[i+1];
            B[i] *=tem;
        }
        return B;
    }

}