AC了

#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#define MAXN 30
using namespace std;
int n,k;
int map[MAXN][MAXN];
int main(){
    memset(map,0x3f,sizeof(map));
    scanf("%d%d",&n,&k);
    for(int i=1;i<=n;i++){
        int x;
        scanf("%d",&x);
        map[i][i%n+1]=map[i%n+1][i]=x;
    }
    for(int i=1;i<=k;i++){
        char a,b;int x;
        cin>>a>>b>>x;
        if(map[a-'A'+1][b-'A'+1]<1000)    map[a-'A'+1][b-'A'+1]=map[b-'A'+1][a-'A'+1]=max(map[a-'A'+1][b-'A'+1],x);
        else map[a-'A'+1][b-'A'+1]=map[b-'A'+1][a-'A'+1]=x;
    }
    for(int i=1;i<=n;i++)
        if(map[i][i]>1000)    map[i][i]=0;
    for(int k=1;k<=n;k++)
        for(int i=1;i<=n;i++)
            for(int j=1;j<=n;j++)
                if(i!=j&&i!=k&&j!=k&&map[i][j]>map[i][k]+map[k][j])
                    map[j][i]=map[i][j]=map[i][k]+map[k][j];
    char a,b;
    cin>>a>>b;
    cout<<map[a-'A'+1][b-'A'+1];
}