http://acm.timus.ru/problem.aspx?space=1&num=1982

题解：最小生成树

/*
*@Author:   STZG
*@Language: C++
*/
#include <bits/stdc++.h>
#include<iostream>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<string>
#include<vector>
#include<bitset>
#include<queue>
#include<deque>
#include<stack>
#include<cmath>
#include<list>
#include<map>
#include<set>
//#define DEBUG
#define RI register int
#define endl "\n"
using namespace std;
typedef long long ll;
//typedef __int128 lll;
const int N=100000+10;
const int M=100000+10;
const int MOD=1e9+7;
const double PI = acos(-1.0);
const double EXP = 1E-8;
const int INF = 0x3f3f3f3f;
int t,n,m,k,p,l,r,u,v;
int ans,cnt,flag,temp,sum;
int pre[N],a[N];
char str;
struct node{
    int u,v,w;
    bool operator<(const node&S)const{
        return w<S.w;
    }
}e[N];
int find(int x){return pre[x]==x?x:pre[x]=find(pre[x]);}
bool marge(int u,int v){
    int tu=find(u);
    int tv=find(v);
    if(tu!=tv){
        pre[tu]=tv;
        return 1;
    }
    return 0;
}
int main()
{
#ifdef DEBUG
	freopen("input.in", "r", stdin);
	//freopen("output.out", "w", stdout);
#endif
    //ios::sync_with_stdio(false);
    //cin.tie(0);
    //cout.tie(0);
    //scanf("%d",&t);
    //while(t--){
    scanf("%d%d",&n,&k);
    for(int i=1;i<=n;i++){
       pre[i]=i;
    }
    for(int i=1;i<=k;i++){
       scanf("%d",&a[i]);
       if(i!=1)marge(a[i-1],a[i]);
    }
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
           scanf("%d",&m);
           if(i<=j)
                continue;
           e[++cnt].u=i;
           e[cnt].v=j;
           e[cnt].w=m;
        }
    }
    sort(e+1,e+cnt+1);
    for(int i=1;i<=cnt;i++){
        if(marge(e[i].u,e[i].v)){
            ans+=e[i].w;
        }
    }
    cout<<ans<<endl;
    //}

#ifdef DEBUG
	printf("Time cost : %lf s\n",(double)clock()/CLOCKS_PER_SEC);
#endif
    //cout << "Hello world!" << endl;
    return 0;
}