单源最短路径算法

堆优化Dijkstra

每次取出一个离起点最近的店进行松弛操作

struct edge{
    int u,w,next;
}e[maxm];

struct node{
	int d,u;
	bool operator < (const node& r) const {
	return d>r.d;
	}
};

int cnt=0,n,m,s;
int head[maxn];
bool vis[maxn];
int dis[maxn];

void add(int a,int b,int c){
    cnt++;
    e[cnt].u=b;
    e[cnt].w=c;
    e[cnt].next=head[a];
    head[a]=cnt;
}

void dijkstra(){
	priority_queue<node>q;
    int cur=s;
    dis[s]=0;;
    q.push((node){0,s});
    while(!q.empty()){
    	node x=q.top();
		q.pop();
		cur=x.u;
		if(vis[cur])continue;
        vis[cur]=true;
        for(int i=head[cur];i!=0;i=e[i].next)
            if(!vis[e[i].u]){
            	dis[e[i].u]=min(dis[e[i].u],dis[cur]+e[i].w);
            	q.push((node){dis[e[i].u],e[i].u});
			}
    }   
}