循环法，仅需14行：

#include<bits/stdc++.h>
using namespace std;
int s,t;
double m;
int main(){
	cin>>s>>t;
	for(int i=s+1;i<=t;i++){
		if(i<=2760)m+=0.52;
		else if(i<=4800)m+=0.57;
		else m+=0.82; 
	}
	cout<<fixed<<setprecision(2)<<m;
	return 0;
}

#include<bits/stdc++.h>
using namespace std;
//输入保证正确
//输出看仔细
//所有情况都测
//数组定义，保证正确

int main()
{
	int x , y;
	cin >> x >>y;
	double h=0,f=0;
	if(x<=2760)
	{
		if(y<=2760)
			h=y-x;
		else
			h=2760-x;
		f=1;
	}
	else if(x>=2760&&x<=4800)
	{
		if(y<=4800)
			h=y-x;
		else
			h=4800-x;
		f=2;
	}
	else
		f=3;
	double sum = 0;
	y=y-x;
	int t=1;
//	cout<<x<<" ";
	while(y>0)
	{
//		cout<<fixed << setprecision(2)<<sum<<" ";
		if(t==1)
		{
			if(f==1)
			{
				sum=sum+h*0.52;
			}
			if(f==2)
			{
				sum=sum+h*0.57;
			}
			if(f==3)
			{
				sum=sum+y*0.82;
				y=0;
			}
			y-=h;
		}
		else
		{
			if(f==2)
			{
				if(y>=2040)
				{
					y-=2040;
					sum=sum+2040*0.57;
				}
				else
				{
					sum=sum+y*0.57;
					y=0;
				}
			}
			else
			{
				sum=sum+y*0.82;
				y=0;
			}	
		}
		f++;
		t++;
	}
	cout<<fixed << setprecision(2)<<sum<<endl;
 	return 0;
}