剑指 Offer 66. 构建乘积数组（中等）

题目:

class Solution {
public:
    vector<int> constructArr(vector<int>& a) {
        int len = a.size();
        if(len==0) return {};
        vector<int> b(len, 1);
        for(int i=1;i<len;i++){      //先计算b[i]下三角的乘积。由图可看出b[1]乘的是a[0]
            b[i]=b[i-1]*a[i-1];
        }
        int tmp=1;
        for(int i=len-2;i>=0;i--){      //再计算b[i]上三角的乘积，乘积用tmp存储和迭代。由图可看出b[3]乘的是a[4]
            tmp*=a[i+1];
            b[i]*=tmp;
        }
        return b;
    }
};

作者：Krahets
链接：https://leetcode.cn/problems/gou-jian-cheng-ji-shu-zu-lcof/solutions/208840/mian-shi-ti-66-gou-jian-cheng-ji-shu-zu-biao-ge-fe/
来源：力扣(LeetCode)