题解

#include<iostream>
#include<stdio.h>
using namespace std;
struct node{
	double place,price;
};
node a[12];
int main(){
	double da,c,db,p,ans = 0.0,last = 0.0;
	int n;
	cin >> da >> c >> db >> p >> n;
	for(int i = 1;i <= n;i++){
        cin >> a[i].place >> a[i].price;
    } 
	a[0] = {0,p};
	a[++n] = {da,0};
	for(int i = 1;i <= n;i++){
		if(a[i].place - a[i - 1].place > c * db){
			cout << "No Solution";
			return 0;
		}
	}
	int j;
	for(int i = 0;i < n;i = j){
		for(j = i + 1;j <= n;j++){
			if(a[j].place - a[i].place > c * db){
				j--;
				break;
			}
			if(a[j].price < a[i].price){
                break;
            } 
		}
		if(a[j].price < a[i].price){
			ans += ((a[j].place - a[i].place) / db - last) * a[i].price;
			last = 0;
		}else{
			ans += (c - last) * a[i].price;
			last = c - (a[j].place - a[i].place) / db;
		}
	}
	printf("%.2lf",ans);
	return 0;
}