题目描述:https://www.nowcoder.com/practice/94a4d381a68b47b7a8bed86f2975db46?tpId=13&&tqId=11204&rp=1&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking

  思路:直接求出这个数组的前缀积和后缀积,然后根据题目要求直接计算即可,需要注意边界(越界)问题。

import java.util.ArrayList;
public class Solution {
    public int[] multiply(int[] A) {
        if(A == null || A.length == 0) return new int[0];
        int n = A.length;
        int[] pre = new int[n], suf = new int[n];
        pre[0] = A[0]; suf[n - 1] = A[n - 1];
        for(int i  = 1 ; i < n; ++ i) {
            pre[i] = pre[i - 1] * A[i];
        }
        for(int i = n - 2; i >= 0; -- i) {
            suf[i] = suf[i + 1] * A[i];
        }
        int[] B = new int[n];
        for(int i = 0; i < n; ++ i) {
            B[i] = (i == 0 ? 1 : pre[i - 1]) * (i == n - 1 ? 1 : suf[i + 1]);
        }
        return B;
    }
}