“玲珑杯”ACM比赛 Round #13

#include <cstdio>
#include <iostream>
#include <algorithm>
using namespace std;
long long a[500010];
long long b[500010];
int main()
{
int n;
scanf("%d",&n);
for (int i=0; i<n; i++)
{
scanf("%lld",&a[i]);
}
for (int i=0; i<n; i++)
{
scanf("%lld",&b[i]);
}
sort(a,a+n);
sort(b,b+n);
long long sum = 0;
for (int i=n-1; i>=0; i--)
{
//必须用long long 数组存不然中途会造成溢出
sum += a[i] * b[i];
}
printf("%lld\n",sum);
return 0;
}