根据数据范围选取spfa求其它所有点到该点的最小距离

#include<bits/stdc++.h>
using namespace std;

const int N = 810,M = 3000,INF = 0x3f3f3f3f;
int id[N];
int h[N],e[M],ne[M],w[M],idx;
bool st[N];
int dist[N];
int n,p,m;

void add(int a,int b,int c)
{
    e[idx] = b,ne[idx] = h[a],w[idx] = c,h[a] = idx++;
}

int spfa(int start)
{
    memset(st,0,sizeof st);
    memset(dist,0x3f,sizeof dist);
    dist[start] = 0;
    queue<int> q;
    q.push(start);
    st[start] = true;

    while(q.size())
    {
        int t = q.front();
        q.pop();
        st[t] = false;

        for(int i = h[t];~i;i = ne[i])
        {
            int j = e[i];
            if(dist[j] > dist[t] + w[i])
            {
                dist[j] = dist[t] + w[i];
                if(!st[j])
                {
                    q.push(j);
                    st[j] = true;
                }
            }
        }
    }

    int res = 0;
    for(int i = 0;i<n;i++)
    {
        int j = id[i];
        if(dist[j] == INF)return INF;
        else res += dist[j];
    }
    return res;
}

int main()
{
    memset(h,-1,sizeof h);
    cin>>n>>p>>m;
    for(int i = 0;i<n;i++)cin>>id[i];

    while(m--)
    {
        int a,b,c;
        cin>>a>>b>>c;
        add(a,b,c),add(b,a,c);
    }

    int res = INF;
    for(int i = 1;i<=p;i++)res = min(res,spfa(i));
    cout<<res<<endl;
    return 0;
}