CF545E.Paths and Trees

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题目描述

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)G=(V,E) (here VV is the set of vertices, EE is the set of edges). The shortest-path tree from vertex uu is such graph G1=(V,E1)G_{1}=(V,E_{1}) that is a tree with the set of edges E1E_{1} that is the subset of the set of edges of the initial graph EE , and the lengths of the shortest paths from uu to any vertex to GG and to G1G_{1} are the same.

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

输入格式

The first line contains two numbers, nn and mm ( 1<=n<=31051<=n<=3·10^{5} , 0<=m<=31050<=m<=3·10^{5} ) — the number of vertices and edges of the graph, respectively.

Next mm lines contain three integers each, representing an edge — ui,vi,wiu_{i},v_{i},w_{i} — the numbers of vertices connected by an edge and the weight of the edge ( uivi,1<=wi<=109u_{i}≠v_{i},1<=w_{i}<=10^{9} ). 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 uu ( 1<=u<=n1<=u<=n ) — the number of the start vertex.

输出格式

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 11 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.

输入输出样例

  • 输入#1

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

    输出#1

    2
    1 2 
    
  • 输入#2

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

    输出#2

    4
    2 3 4 
    

说明/提示

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

  • with edges 131–3 and 232–3 (the total weight is 33 );
  • with edges 121–2 and 232–3 (the total weight is 22 );

And, for example, a tree with edges 121–2 and 131–3 won't be a shortest path tree for vertex 33 , because the distance from vertex 33 to vertex 22 in this tree equals 33 , and in the original graph it is 11 .

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