构建乘积数组

先将每个A[i]用temp值保存起来，再置为1进行相乘，赋给B[i]
时间复杂度为 O(n的二次方)

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