I

Think:
1知识点：最短路_spfa算法(多起点-多终点)
2思考：将起点vis置为1,dis置为0,spfa算法,然后dis数组取多终点中的最小值
3优化思路：创建源点0和汇点n+1，将源点0与所有起点连边(无向边),边权为0，将所有终点与汇点n+1连边(无向边),边权为0；然后spfa算法求0点到n+1点的最短路即可

vjudge题目链接

以下为Accepted代码——多起点_多终点

#include <cstdio>#include <cstring>#include <algorithm>#include <queue>using namespace std;const int inf = 0x3f3f3f3f;const int N = 1e5 + 4e2;const int M = 1e5 + 4e2;struct Edge{    int v;    int w;    int next;}edge[M];int cnt, head[N], vis[N], dis[N], a[N], b[N];int op, tp, link[N];void Init(int n);void add_edge(int u, int v, int w);void spfa();int main(){    int n, m, i, u, v, w, len_a, len_b;    while(~scanf("%d %d", &n, &m)){        cnt = 0;        Init(n);        while(m--){            scanf("%d %d %d", &u, &v, &w);            add_edge(u, v, w);        }        memset(vis, 0, sizeof(vis));        memset(dis, inf, sizeof(dis));        scanf("%d", &len_a);        op = tp = 0;        for(i = 0; i < len_a; i++){            scanf("%d", &a[i]);            vis[a[i]] = 1;            dis[a[i]] = 0;            link[tp++] = a[i];        }        scanf("%d", &len_b);        for(i = 0; i < len_b; i++){            scanf("%d", &b[i]);        }        spfa();        int miv = inf;        for(i = 0; i < len_b; i++){            miv = min(miv, dis[b[i]]);        }        printf("%d\n", miv);    }    return 0;}void Init(int n){    for(int i = 1; i <= n; i++)        head[i] = -1;}void add_edge(int u, int v, int w){    edge[cnt].v = v;    edge[cnt].w = w;    edge[cnt].next = head[u];    head[u] = cnt++;}void spfa(){    while(op < tp){        int u = link[op];        vis[u] = 0;        for(int i = head[u]; ~i; i = edge[i].next){            int v = edge[i].v;            int w = edge[i].w;            if(dis[u] + w < dis[v]){                dis[v] = dis[u] + w;                if(!vis[v]){                    vis[v] = 1;                    link[tp++] = v;                }            }        }        op++;    }}