C++ 解法, 执行用时: 1ms, 内存消耗: 376KB, 提交时间: 2020-07-07

/**
 * 运行时间：4ms
 * 占用内存：504k
*/
#include <cstdio>
#include <iostream>
#include <utility>
#include <vector>

using namespace std;

class Solution {
private:
    unsigned out;

public:
    Solution(const vector<int>& prices, const vector<pair<int, int>>& goods);
    ~Solution();
    friend ostream& operator<<(ostream& os, const Solution& s);
};

Solution::Solution(const vector<int>& prices, const vector<pair<int, int>>& goods)
    : out(0)
{
    for (const pair<int, int>& i : goods) {
        out += i.second * prices[i.first];
    }
}

Solution::~Solution()
{
}

ostream& operator<<(ostream& os, const Solution& s)
{
    // os << s.out;
    printf("%d", s.out);
    return os;
}

int main(int argc, char* argv[])
{
    int n;
    // cin >> n;
    scanf("%d", &n);
    vector<int> prices(n + 1, 0);
    for (size_t i = 1; i <= n; i++) {
        // cin >> prices[i];
        scanf("%d", &prices[i]);
    }

    int m;
    // cin >> m;
    scanf("%d", &m);
    vector<pair<int, int>> goods(m, make_pair(0, 0));
    for (size_t i = 0; i < m; i++) {
        // cin >> goods[i].first >> goods[i].second;
        scanf("%d %d", &goods[i].first, &goods[i].second);
    }

    Solution s(prices, goods);

    cout << s << endl;
    return 0;
}

C 解法, 执行用时: 2ms, 内存消耗: 232KB, 提交时间: 2019-01-22

#include<stdio.h>

int main()
{
    int n;
    scanf("%d",&n);
    int ai[n];
    for(int i=0;i<n;i++)
    {
        scanf("%d",&ai[i]);
    }
    int k;
    scanf("%d",&k);
    int sum =0;
    for(int j=0;j<k;j++)
 //   while(k--)
    {
       int a1,a2;
       scanf("%d%d",&a1,&a2);
       sum = sum+ai[a1-1]*a2;
    }
    printf("%d",sum);
    return 0;
}