HackerRank Breadth First Search: Shortest Reach - James Pan - 博客频道 - CSDN.NET
https://www.hackerrank.com/challenges/bfsshortreach
https://www.hackerearth.com/notes/graph-theory-breadth-first-search/
http://akshikaspace.blogspot.com/2016/04/hackerrank-breadth-first-search.html
Read full article from HackerRank Breadth First Search: Shortest Reach - James Pan - 博客频道 - CSDN.NET
https://www.hackerrank.com/challenges/bfsshortreach
Given an undirected graph consisting of nodes (labelled 1 to N) where a specific given node represents the start position and an edge between any two nodes is of length units in the graph.
It is required to calculate the shortest distance from start position (Node S) to all of the other nodes in the graph.
Note 1: If a node is unreachable , the distance is assumed as .
Note 2: The length of each edge in the graph is units.
Note 2: The length of each edge in the graph is units.
Input Format
The first line contains , denoting the number of test cases.
First line of each test case has two integers , denoting the number of nodes in the graph and , denoting the number of edges in the graph.
The next lines each consist of two space separated integers , where and denote the two nodes between which the edge exists.
The last line of a testcase has an integer , denoting the starting position.
First line of each test case has two integers , denoting the number of nodes in the graph and , denoting the number of edges in the graph.
The next lines each consist of two space separated integers , where and denote the two nodes between which the edge exists.
The last line of a testcase has an integer , denoting the starting position.
Constraints
Output Format
For each of test cases, print a single line consisting of space-separated integers, denoting the shortest distances of the N-1 nodes from starting position . This will be done for all nodes same as in the order of input 1 to N.
For unreachable nodes, print .
Sample Input
2
4 2
1 2
1 3
1
3 1
2 3
2
Sample Output
6 6 -1
-1 6
Explanation
For test cases 1:
The graph given in the test case is shown as :
S denotes the node 1 in the test case and B,C and D denote 2,3 and 4. Since S is the starting node and the shortest distances from it are (1 edge, 1 edge, Infinity) to the nodes B,C and D (2,3 and 4) respectively.
Node D is unreachable, hence -1 is printed (not Infinity).
For test cases 2: There are only one edge (2, 3) in a graph with 3 nodes, so node 1 is unreachable from node 2, and node 3 has one edge from node 2, each edge has the
length of 6 units. So we output -1 6.
length of 6 units. So we output -1 6.
http://akshikaspace.blogspot.com/2016/04/hackerrank-breadth-first-search.html
Read full article from HackerRank Breadth First Search: Shortest Reach - James Pan - 博客频道 - CSDN.NET
