hdu2680

设置虚拟的点0，让他与所有的起点相连距离为0 就相当与从0点出发 找最短路；


#include <iostream>
#include <cstdio>
#include <cstring>
#include <queue>
using namespace std;
const int _max = 0x3f3f3f3f;
const int maxn = 1000+10;
int map[maxn][maxn];
bool visit[maxn];
int dist[maxn];
int n, m, des;

void SPFA()
{
    queue<int>q;
    for(int i = 0; i <= n; i++)
        dist[i] = _max;
    dist[0] = 0;
    visit[0] = true;
    q.push(0);
    while(!q.empty())
    {
        int cur = q.front();
        q.pop();
        visit[cur] = false;
        for(int i = 0; i <= n; i++)
            if(dist[i]>dist[cur]+map[cur][i])
            {
                dist[i] = dist[cur]+map[cur][i];
                if(!visit[i])
                {
                    q.push(i);
                    visit[i] = true;
                }
            }
    }
    if(dist[des]<_max)
        printf("%d\n", dist[des]);
    else printf("-1\n");
}

int main()
{
    while(scanf("%d%d%d", &n, &m, &des)!=EOF)
    {
        for(int i = 0; i <= n; i++)
            for(int j = 0; j <= n; j++)
                map[i][j] = _max;
        for(int i = 1; i <= m; i++)
        {
            int u, v, w;
            scanf("%d%d%d", &u, &v, &w);
            if(map[u][v] > w) map[u][v] = w;
        }
        int f;
        scanf("%d", &f);
        for(int i = 1; i <= f; i++)
        {
            int v;
            scanf("%d", &v);
            map[0][v] = 0;
        }
        memset(visit, false, sizeof(visit));
        SPFA();
    }
}