【模板】dijkstra

洛谷 4779

 #include<cstdio>
 #include<cstring>
 #include<algorithm>
 #include<queue>
 #define N 100010
 #define rg register
 using namespace std;
 int n,m,s,tot,last[N],dis[N];
 struct edge{int to,pre,dis;}e[];
 struct node{
     int poi,dis;
     bool operator <(const node& rhs)const {return dis>rhs.dis;}
 };
 priority_queue<node>q;
 inline int read(){
     int k=,f=; char c=getchar();
     while(c<''||c>'')c=='-'&&(f=-),c=getchar();
     while(''<=c&&c<='')k=k*+c-'',c=getchar();
     return k*f;
 }
 inline void dijkstra(int x){
     for(rg int i=;i<=n;i++) dis[i]=1e9+;
     q.push((node){x,dis[x]=});
     while(!q.empty()){
         node tmp=q.top(); q.pop();
         int now=tmp.poi;
         if(dis[now]!=tmp.dis) continue;
         for(rg int i=last[now],to;i;i=e[i].pre)if(dis[to=e[i].to]>dis[now]+e[i].dis){
             dis[to]=dis[now]+e[i].dis;
             q.push((node){to,dis[to]});
         }
     }
 }
 int main(){
     n=read(); m=read(); s=read();
     for(rg int i=;i<=m;i++){
         int u=read(),v=read();
         e[++tot]=(edge){v,last[u],read()}; last[u]=tot;
     }
     dijkstra(s);
     for(rg int i=;i<=n;i++) printf("%d ",dis[i]);
     return ;
 }

手写堆的版本

 #include<cstdio>
 #include<algorithm>
 #define N 100010
 #define rg register
 #define LL long long
 using namespace std;
 int n,m,s,tot,fa,son,last[N],pos[N],dis[N];
 struct edge{int to,pre,dis;}e[];
 struct heap{int poi,dis;}h[N];
 inline int read(){
     int k=,f=; char c=getchar();
     while(c<''||c>'')c=='-'&&(f=-),c=getchar();
     while(''<=c&&c<='')k=k*+c-'',c=getchar();
     return k*f;
 }
 inline void up(int x){
     while((fa=x>>)&&h[fa].dis>h[x].dis)
         swap(h[x],h[fa]),swap(pos[h[x].poi],pos[h[fa].poi]),x=fa;
 }
 inline void down(int x){
     while((son=x<<)<=tot){
         if(h[son].dis>h[son+].dis&&son<tot) son++;
         if(h[son].dis<h[x].dis) swap(h[son],h[x]),swap(pos[h[son].poi],pos[h[x].poi]),x=son;
         else return;
     }
 }
 inline void dijkstra(int x){
     for(rg int i=;i<=n;i++) dis[i]=1e9+;
     h[pos[x]=tot=]=(heap){x,dis[x]=};
     while(tot){
         int now=h[].poi; pos[h[tot].poi]=; h[]=h[tot--]; if(tot) down();
         for(rg int i=last[now],to;i;i=e[i].pre)if(dis[to=e[i].to]>dis[now]+e[i].dis){
             dis[to]=dis[now]+e[i].dis;
             if(!pos[to]) h[pos[to]=++tot]=(heap){to,dis[to]};
             else h[pos[to]].dis=dis[to];
             up(pos[to]);
         }
     }
 }
 int main(){
     n=read(); m=read(); s=read();
     for(rg int i=;i<=m;i++){
         int u=read(),v=read();
         e[++tot]=(edge){v,last[u],read()}; last[u]=tot;
     }
     dijkstra(s);
     for(rg int i=;i<=n;i++) printf("%d ",dis[i]);
     return ;
 }