P4779 【模板】单源最短路径

题目地址

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注意点：

• 源点需要设置初始距离（0）.
• 优先队列默认是从大到小排序，因此需要重载运算符.

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#include<cstdio>
#include<iostream>
#include<queue>
using namespace std;
const int MAXN=1000010,MAXM=1000010;
struct Edge{
	int from,to,w,nxt;
}e[MAXM];
int head[MAXN],edgeCnt=1;
void addEdge(int u,int v,int w){
	e[++edgeCnt].from=u;
	e[edgeCnt].to=v;
	e[edgeCnt].w=w;
	e[edgeCnt].nxt=head[u];
	head[u]=edgeCnt;
}
int s;
struct Node{
	int nowPoint,dis;
	bool operator <(Node another)const{
		return dis>another.dis;
	}
};
int dis[MAXN];
void dijkstra(){
	priority_queue<Node> q;
	q.push(Node{s,0});
	dis[s]=0;
	while(!q.empty()){
		Node nowNode=q.top();q.pop();
		int nowPoint=nowNode.nowPoint,nowDis=nowNode.dis;
		if(nowDis>dis[nowPoint])continue;
		for(int i=head[nowPoint];i;i=e[i].nxt){
			int nowV=e[i].to;
			if(dis[nowPoint]+e[i].w<dis[nowV]){
				q.push(Node{nowV,dis[nowPoint]+e[i].w});
				dis[nowV]=dis[nowPoint]+e[i].w;
			}
		}
	}
}
const int INF=2e9;
int main(){
	int n,m;
	scanf("%d%d%d",&n,&m,&s);
	for(int i=1;i<=n;i++)dis[i]=INF;
	for(int i=1;i<=m;i++){
		int u,v,w;
		scanf("%d%d%d",&u,&v,&w);
		addEdge(u,v,w);
	}
	dijkstra();
	for(int i=1;i<=n;i++){
		printf("%d ",dis[i]);
	}
	printf("
");
	return 0;
}