75分 WA on #5

12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667#include<bits/stdc++.h>
using namespace std;
struct oil
{
	double p,d;
}a[10];
double s,c,l;
double ans=0;
double nowc;//表示当前油量
double cd[10];
int n;
bool cmp(oil x,oil y)
{
	return x.d<y.d;
}
int main()
{
	cin>>s>>c>>l>>a[0].p>>n;
	for(int i = 1;i <= n;i++)
	{
		cin>>a[i].d>>a[i].p;
	}
	sort(a+1,a+n+1,cmp);
	for(int i = 1;i <= n;i++)
	{
		cd[i]=a[i].d-a[i-1].d;
	}
    a[n+1].d=s;
	cd[n+1]=s-a[n].d;
	for(int i = 1;i <= n+1;i++)//判断能否到达
	{
		if(cd[i]>c*l)
		{
			cout<<"No Solution";
			return 0;
		}
	}
	for(int i = 0;i <= n;i++)
	{
		int nextlower;//到达终点一定比他便宜
		double distancelower;//距离
		for(int j = i+1;j <= n+1;j++)
		{
			if(a[j].p<a[i].p)//比当前便宜
			{
				nextlower=j;
				break;
			}
		}
		distancelower=a[nextlower].d-a[i].d;
		//可以直接一口气冲到下一个比当前便宜的加油站
		//把油加到刚刚好到地
		if(distancelower<=c*l)
		{
            // cout<<nowc<<" "<<distancelower<<"\n";
			ans+=max(1.0*distancelower/l-nowc,0.0)*a[i].p;
			nowc=0;
            i=nextlower-1;
            nowc=0;
		}
		else //把油加满，
		{
			ans+=(c-nowc)*a[i].p;
            nowc=c-cd[i+1]/l;
        }
	}
	printf("%.2f",ans);
    return 0;
}