RT

#include<iostream> 
using namespace std;
#define int long long
int n,m,p[100005],a[100005],b[100005],c[100005],ans=0,qianzhui[100005],cishu[100005];
int before,now,minn=0;
main(){
	cin>>n>>m;
	for(int i=1;i<=m;i++)
		cin>>p[i];
	for(int i=1;i<=n-1;i++)
		cin>>a[i]>>b[i]>>c[i];
	before=1;
	for(int i=1;i<=m;i++){
		now=p[i];
		if(before>now)
			swap(before,now);
		qianzhui[before]++;
		qianzhui[now]--;
		before=p[i];
	}
	for(int i=1;i<=n-1;i++){
		cishu[i]=cishu[i-1]+qianzhui[i];
		if(cishu[i]*a[i]<cishu[i]*b[i]+c[i])
			minn+=cishu[i]*a[i];
		else
			minn+=cishu[i]*b[i]+c[i];
	}
	cout<<minn;
	return 0;
}

感觉每个点都没什么问题啊