题解

题目比较迷惑，反正不知道怎么就AC了

//#include <cjdst.h>
#include <vector>
#include <memory.h>
#include <queue>
#include <iostream>
#include <cstdio>
const int A = 'A' - 1;
void read(int &);
void read(char &);
void read(int &x){
	char c = getchar();
	x = 0;
	int f = 1;
	while(!isdigit(c)){
		if(c == '-') f = -f;
		c = getchar();
	}
	while(isdigit(c)){
		x = (x << 3) + (x << 1) + c - '0';
		c = getchar();
	}
}
void read(char &c){
	c = getchar();
	while(!isalpha(c)) c = getchar();
}
using namespace std;
struct node{
	int to, len;
	bool operator < (const node &b) const{
		return len > b.len;
	}
};
vector <node> v[21];
int dis[21];
bool vis[21];
int n, m, z;
char k, t, x, y;
int dijkstra(){
	memset(dis, 63, sizeof(dis));
	dis[k] = 0;
	priority_queue <node> q;
	q.push({k, 0});
	while(!q.empty()){
		node head = q.top();
		q.pop();
		if(vis[head.to]) continue;
		vis[head.to] = 1;
		for(node it:v[head.to]){
			if(head.len + it.len < dis[it.to]){
				dis[it.to] = head.len + it.len;
				q.push({it.to, dis[it.to]});
			}
		}
	}
	return dis[t];
}
void push(vector <node> &v, node a){
	for(int i = 0; i < v.size(); i++){
		if(v[i].to == a.to){
			v[i].len = max(v[i].len, a.len);
			return;
		}
	}
	v.push_back(a);
}
int main(){
	read(n), read(m);
	for(int i = 1; i < n; i++){
		read(z);
		v[i].push_back({i + 1, z}), v[i + 1].push_back({i, z});
	}
	read(z);
	v[n].push_back({1, z}), v[1].push_back({n, z});
	for(int i = 1; i <= m; i++){
		read(x), read(y), read(z);
		push(v[x - A], {y - A, z});
		push(v[y - A], {x - A, z});
	}
	read(k), read(t);
	k -= A, t -= A;
	if(k == t){
		for(auto it:v[k]) if(it.to == k) cout << it.len;
	}
	else cout << dijkstra();

	return 0;
}