【luogu P3371 单源最短路径】 模板 SPFA

题目链接：https://www.luogu.org/problemnew/show/P3371

我永远都喜欢Flyod、dijkstra + heap、SPFA

 #include <cstdio>
 #include <cstring>
 #include <queue>
 #include <algorithm>
 using namespace std;
 const int maxn = ;
 const int inf = 0x7fffffff;
 int n, m, s, dis[maxn];
 bool vis[maxn];
 struct edge{
     int to, next, len, from;
 }e[maxn];
 int head[maxn], cnt;
 queue<int> q;
 void add(int u, int v, int w)
 {
     e[++cnt].from = u;
     e[cnt].to = v;
     e[cnt].len = w;
     e[cnt].next = head[u];
     head[u] = cnt;
 }
 int SPFA()
 {
     while(!q.empty())
     {
         int now = q.front();
         q.pop();
         vis[now] = ;
         for(int i = head[now]; i ; i = e[i].next)
         {
             if(dis[e[i].to] > dis[now]+e[i].len)
             {
                 dis[e[i].to] = dis[now]+e[i].len;
                 if(!vis[e[i].to])
                 {
                     vis[e[i].to] = ;
                     q.push(e[i].to);
                 }
             }
         }
     }
 }
 int main()
 {
     scanf("%d%d%d",&n,&m,&s);
     for(int i = ; i <= n; i++)
     dis[i] = inf;
     for(int i = ; i <= m; i++)
     {
         int u,v,w;
         scanf("%d%d%d",&u,&v,&w);
         add(u,v,w);
     }
     dis[s] = ;
     q.push(s);
     vis[s] = ;
     SPFA();
     for(int i = ; i <= n; i++)
     printf("%d ",dis[i]);
 }