Paths and Trees (Dijkstra单源最短路+边权值和最小)

 Little girl Susie accidentally found her elder brother's notebook. She has many things to do, more important than solving problems, but she found this problem too interesting, so she wanted to know its solution and decided to ask you about it. So, the problem statement is as follows.

Let's assume that we are given a connected weighted undirected graph G = (V, E) (here V is the set of vertices, E is the set of edges). The shortest-path tree from vertex u is such graph G1 = (V, E1) that is a tree with the set of edges E1 that is the subset of the set of edges of the initial graph E, and the lengths of the shortest paths from u to any vertex to G and to G1 are the same.

You are given a connected weighted undirected graph G and vertex u. Your task is to find the shortest-path tree of the given graph from vertex u, the total weight of whose edges is minimum possible.

Input

The first line contains two numbers, n and m (1 ≤ n ≤ 3·105, 0 ≤ m ≤ 3·105) — the number of vertices and edges of the graph, respectively.

Next m lines contain three integers each, representing an edge — ui, vi, wi — the numbers of vertices connected by an edge and the weight of the edge (ui ≠ vi, 1 ≤ wi ≤ 109). It is guaranteed that graph is connected and that there is no more than one edge between any pair of vertices.

The last line of the input contains integer u (1 ≤ u ≤ n) — the number of the start vertex.

Output

In the first line print the minimum total weight of the edges of the tree.

In the next line print the indices of the edges that are included in the tree, separated by spaces. The edges are numbered starting from 1 in the order they follow in the input. You may print the numbers of the edges in any order.

If there are multiple answers, print any of them.

Examples

Input

3 3
1 2 1
2 3 1
1 3 2
3

Output

2
1 2 

Input

4 4
1 2 1
2 3 1
3 4 1
4 1 2
4

Output

4
2 3 4 

Note

In the first sample there are two possible shortest path trees:

  • with edges 1 – 3 and 2 – 3 (the total weight is 3);
  • with edges 1 – 2 and 2 – 3 (the total weight is 2);

And, for example, a tree with edges 1 – 2 and 1 – 3 won't be a shortest path tree for vertex 3, because the distance from vertex 3 to vertex 2 in this tree equals 3, and in the original graph it is 1.

题意:

给出n个点m条边的带权无向图,问一个起点到任意点的单源最短路径,走的所有点遍历的所有边的边权总和

还需要输出到达任意点的最短路径是哪些边

注意long long 

#include<cstdio>
#include<queue>
#include<algorithm>
#include<cstring>
#include<vector>
using namespace std;
typedef long long ll;
const ll INF=(1LL<<60)-1;
const int N=3e5+5;
struct node{
	int v,w,id;
	node(int vv=0,int ww=0,int iid=0){
		v=vv;
		w=ww;
		id=iid;
	}
};
struct Node{
	int u;
	ll d;
	Node(int uu=0,ll dd=0){
		u=uu;
		d=dd;
	}
	bool operator<(const Node &a)const{
	     return d>a.d;
	}
};
vector<node>E[N];
bool vis[N];
ll dis[N];
int used[N];
ll cost[N];
void Dijkstra(int n,int start){
	priority_queue<Node> q;
	memset(vis,0,sizeof(vis));
	for(int i=1;i<=n;i++) dis[i]=INF;
	dis[start]=0;
	q.push(Node(start,0));
	while(!q.empty()){
		Node tmp=q.top();
		q.pop();
		int u=tmp.u;
		if(vis[u]) continue;
		vis[u]=true;
		for(int i=0;i<E[u].size();i++){
			int v=E[u][i].v;
			int w=E[u][i].w;
			int id=E[u][i].id;
			if(!vis[v]&&dis[v]>dis[u]+w){
				dis[v]=dis[u]+w;
				cost[v]=w;
				used[v]=id;
				q.push(Node(v,dis[v]));
			}
			else if(!vis[v]&&dis[v]==dis[u]+w){
				if(cost[v]>w){
					cost[v]=w;
					used[v]=id;
					q.push(Node(v,dis[v]));
				}
			}
		}
	}
	ll ans=0;
	for(int i=1;i<=n;i++) ans+=cost[i];
	printf("%I64d\n",ans);
	for(int i=1;i<=n;i++){
		if(i!=start) printf("%d ",used[i]);
	}
	printf("\n");
}
int main(){
	int n,m;
	scanf("%d%d",&n,&m);
	for(int i=1;i<=m;i++){
		int u,v,w;
		scanf("%d%d%d",&u,&v,&w);
		E[u].push_back(node(v,w,i));
		E[v].push_back(node(u,w,i));
	}
	int start;
	scanf("%d",&start);
	Dijkstra(n,start);
	return 0;
}

 

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01-16 18:34
四川大学 Java
欢迎加入AI:没有啥稳定不稳定,一切都源于业务快速发展还是收缩。我当年一开始去的央企,业务不赚钱,也贼卷,慢慢就开始优化了。。。
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神哥了不得:你简历字体有点不太协调呀,下面的字实在太小了呀,而且项目也不太行,建议换几个高质量的项目,面试会多很多
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上去投简历,什么的都准备好了,但是就是反馈率很低,处理的非常慢。而且还卖我的信息,有些公司没投就直接电话找我。真成失联招聘了?
Ethan伊森:真的,虽然天天看到吐槽boss,但是boss一周就约了好几个面试,hr交流反馈都很及时,智联有那个一键投简历,投的比boss多得多,却一个联系约面的都没有
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