luogu_P1016 旅行家的预算

贪心，很有难度！！！

#include<iostream>
#include<cstdio>

#define ri register int
#define u int

namespace opt {
    
    inline u in() {
        u x(0),f(1);
        char s=getchar();
        while(s<'0'||s>'9') {
            if(s=='-')f=-1;
            s=getchar();
        }
        while(s>='0'&&s<='9') {
            x=(x<<1)+(x<<3)+s-'0';
            s=getchar();
        }
        return x*f;
    }
    
    u pow[10]= {1};
    
    inline double dbin() {
        u x(0),y(0),cnt(0),f(1);
        char s=getchar();
        while(s<'0'||s>'9') {
            if(s=='-') f=-1;
            s=getchar();
        }
        while(s>='0'&&s<='9') {
            x=(x<<1)+(x<<3)+s-'0';
            s=getchar();
        }
        s=getchar();
        while(s>='0'&&s<='9') {
            ++cnt,y=(y<<1)+(y<<3)+s-'0';
            s=getchar();
        }
        return f*(x+((double)y)/pow[cnt]);
    }

}

using opt::dbin;
using opt::in;

#include<algorithm>
#include<cstring>

#define NN 505

namespace mainstay {
    
    double D1,C,D2,P,re,rest,d[NN],p[NN]; 
    
    u N;

    inline void solve() {
        for(ri i(1); i<=8; ++i) opt::pow[i]=opt::pow[i-1]*10;
        D1=dbin(),C=dbin(),D2=dbin(),p[0]=dbin(),N=in(),d[N+1]=D1;
        //距离D1，容量C，D2 km/l 
        for(ri i(1);i<=N;++i) d[i]=dbin(),p[i]=dbin();//d据起点距离，p价钱 
        for(ri i(0);i<=N;++i){
            if(C*D2<d[i+1]-d[i]) {//中途夭折，加满油都到不了下一个油站。。。 
                printf("No Solution");
                return;
            }
            double to(d[i]+C*D2);
            u poi(i);//在当前点加满油到达的最右 ，poi：最划算的点
            for(ri j(i+1);j<=N+1;++j){
                if(d[j]<=to&&p[j]<p[i]){//在最右内且油价更便宜 
                    poi=j;
                    break;
                }
            }
            if(poi^i) {
                if(rest<(d[poi]-d[i])/D2) re+=((d[poi]-d[i])/D2-rest)*p[i],rest=(d[poi]-d[i])/D2;
            }
            else re+=(C-rest)*p[i],rest=C;
            rest-=(d[i+1]-d[i])/D2;
        }
        printf("%.2f",re);
    }

}

int main() {

    //freopen("x.txt","r",stdin);
    mainstay::solve();

}