题意

• 给一个数组, 计算不包含nums[i]的数组的乘积,

方法

• 记录数组中零的数量和索引

代码

class Solution {
public:
    vector<int> productExceptSelf(vector<int>& nums) {
        bool zero_idx[100024];
        int zero_nums = 0;
        memset(zero_idx, 0, sizeof(zero_idx));
        int product_all = 1, N = nums.size();
        for (int i = 0; i < N; i++) {
            if (nums[i] == 0) {
                zero_idx[i] = true;
                zero_nums++;
                continue;
            }
            product_all *= nums[i];
        }
        
        vector<int> ans;
        for (int i = 0; i < N; i++) {
            if (zero_nums > 1) {
                ans.push_back(0);
            }
            else if (zero_idx[i] == true || zero_nums == 0) {
                int product_res = product_all;
                if (nums[i]) product_res /= nums[i];
                ans.push_back(product_res);
            }
            else ans.push_back(0);
        }

        return ans;
    }
};