codeforce 702D Road to Post Office 物理计算路程题

http://codeforces.com/contest/702

题意：人到邮局去，距离d，汽车在出故障前能跑k，汽车1公里耗时a，人每公里耗时b，修理汽车时间t，问到达终点最短时间

思路：计算车和人的平均速度，谁快用谁，最后特判<=k的距离

 // #pragma comment(linker, "/STACK:102c000000,102c000000")
 #include <iostream>
 #include <cstdio>
 #include <cstring>
 #include <sstream>
 #include <string>
 #include <algorithm>
 #include <list>
 #include <map>
 #include <vector>
 #include <queue>
 #include <stack>
 #include <cmath>
 #include <cstdlib>
 // #include <conio.h>
 using namespace std;
 #define pi acos(-1.0)
 const int N = 1e5+;
 const int MOD = 1e9+;
 #define inf 0x7fffffff
 typedef long long  LL;

 void frein(){freopen("in.txt","r",stdin);}
 void freout(){freopen("out.txt","w",stdout);}
 inline int read(){int x=,f=;char ch=getchar();while(ch>''||ch<'') {if(ch=='-') f=-;ch=getchar();}while(ch>=''&&ch<='') { x=x*+ch-'';ch=getchar();}return x*f;}

 int a[N];
 int b[N];

 int main(){
     LL d,k,a,b,t;
     cin>>d>>k>>a>>b>>t;
     if((d-d%k)<=){
         printf("%I64d\n",a*d);
         exit();
     }
     LL ans1,ans2;
     if((double)(1.0*(k*a+t)/k)<b){
         ans1=(d-d%k)*a+(d/k-)*t;
         d-=d/k*k;
         ans2=min(a*d+t,b*d);
     }
     else {
         ans1=(d-k)*b;
         ans2=k*min(a,b);
     }
     printf("%I64d\n",ans1+ans2);
     return ;
 }