I - 浪里个浪 FZU - 2261——最短路_spfa算法(多起点-多终点)

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 
#include 
#include 
#include 

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++;
    }
}