7-39 魔法优惠券 (25分)--sort()

//sort(a+i,a+j)------->a[i]到a[j-1]被排序。
 1 #include <iostream>
#include <algorithm>

using namespace std;
long int pos[1000001], neg[1000001],price[1000001];
long int N, M;
long int k1 = -1, k2 = -1;
long int p1 = -1, p2 = -1;
bool cmp_less(long int a,long int b)
{
    return a > b;
}
bool cmp_greater(long int a, long int b)
{
    return a < b;
}
int main()
{
    cin >> N;
    for (long int i = 0; i < N; i++)
    {
        long int temp; cin >> temp;
        if (temp > 0)
        {
            pos[++k1] = temp;
        }
        else
        {
            neg[++k2] = temp;
        }
    }
    cin >> M;
    for (long int i = 0; i < M; i++)
    {
        cin >> price[i];
    }
    sort(pos, pos + N,cmp_less);
    sort(neg, neg + N, cmp_greater);
    sort(price, price + M, cmp_less);
    long int sum = 0;
    long int p = M - 1;
    long int flag = 0;

    for (long int i = 0; i < M; i++)
    {
        if (price[i] < 0 && flag == 0)
        {    
            sort(price + i, price + M, cmp_greater);
            flag = 1;
        }
        if (price[i] > 0)
        {
            if (k1 != p1)
            {
                sum += price[i] * pos[++p1];
            }
        }
        if (price[i] < 0)
        {
            if (k2 != p2)
            {
                sum += price[i] * neg[++p2];
            }
        }
    }
    cout << sum;
    return 0;
}