[Nowcoder] 最大乘积（拼多多笔试题）

#include <iostream>
#include <vector>
#include <climits>
#include <cmath>
using namespace std;

int main()
{
    int n;
    while (cin >> n)
    {
        vector<long long> nums(n, 0);
        // 读取输入
        for (int i = 0; i < n; ++i)
        {
            cin >> nums[i];
        }
        // 定义需要计算的数值
        long long max1 = 0, max2 = 0, max3 = 0, min1 = 0, min2 = 0, res1 = 0, res2 = 0;
        // 比较数组前三个数找出其中的大小关系来确定五个数
        max1 = max(nums[0], nums[1]);
        max2 = min(nums[0], nums[1]);
        if (nums[2] > max1)
        {
            max3 = max2;
            max2 = max1;
            max1 = nums[2];
        }
        else if (nums[2] > max2)
        {
            max3 = max2;
            max2 = nums[2];
        }
        else
            max3 = nums[2];
        min1 = max3;
        min2 = max2;
        // 根据前面确定的关系遍历数组。更新五个目标值
        for (int i = 3; i < n; ++i)
        {
            if (nums[i] < min1)
            {
                min2 = min1;
                min1 = nums[i];
            }
            else if (nums[i] < min2)
            {
                min2 = nums[i];
            }
            if (nums[i] > max1)
            {
                max3 = max2;
                max2 = max1;
                max1 = nums[i];
            }
            else if (nums[i] > max2)
            {
                max3 = max2;
                max2 = nums[i];
            }
            else if (nums[i] > max3)
                max3 = nums[i];
        }
        // 计算三个最大数的乘积
        res1 = max1 * max2 * max3;
        // 计算一个最大数和两个最小数的乘积
        res2 = max1 * min1 * min2;
        // 输出结果
        cout << max(res1, res2) << endl;
        return 0;
    }
}