题解

#include <iostream>
using namespace std;
double w, l;
int n;
double a[1100], b[1100], f[1100];

int main()
{
	cin >> w >> l >> n;
	for (int i = 1; i <= n; i++)
	{
		cin >> a[i] >> b[i];
		f[i] = 99999999999999999;
	}
	f[1] = l / b[1] * 60;
	f[0] = 0;
	for (int i = 2; i <= n; i++)
	{
		double weight = 0;
		double ms = b[i];
		for (int j = i; j >= 1; j--)
		{
			weight += a[j];
			if (weight > w)
				break;
			if (b[j] < ms)
				ms = b[j];
			f[i] = min(f[i], f[j - 1] + l / ms * 60);
		}
	}
	printf("%.1f", f[n]);
	return 0;
}