精打细算

 

#include <iostream>
#include <algorithm>
using namespace std;
const int N = 1000;
int n, m;
int v[N], w[N];
int f[N];
int main()
{
void fun();
cin >> n >> m;
for (int i = 1; i <= m; i++)
{
cin >> v[i] >> w[i];
w[i] *= v[i];
}
for (int i = 1; i <= m; i++)
for (int j = n; j >= v[i]; j--)
f[j] = max(f[j], f[j - v[i]] + w[i]);
cout << f[n] << endl;
return 0;
}