蒟蒻受大佬启发改的代码，拿去 ~~（先看读不读的懂）~~
```cpp
#include<bits/stdc++.h>
using namespace std;
int n,m,p,c[100005],p2,p1,a,b,c1;
long long sum,ans;
int main()
{
cin>>n>>m;
if(m>0)cin>>p1;
for(int i=2;i<=m;i++)
{
cin>>p2;
if(p1<p2)c[p1]++,c[p2]--;
else c[p2]++,c[p1]--;
p1=p2;
}
for(int i=1;i<n;i++)
{
sum+=c[i];
cin>>a>>b>>c1;
if(sum!=0)ans+=min(a*sum,b*sum+c1);
}
if(m<=1)ans=0;
cout<<ans;
return 0;
}
```
by wcy123bc @ 2023-09-26 20:46:06