构建乘积数组

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