/// <summary>
/// Breadth-first search for closest black node to given root node.
/// </summary>
/// <param name="nodes">List of nodes with neighbors</param>
/// <param name="root">Root node</param>
/// <returns></returns>
private static ClosestNode Search(IReadOnlyList <Node> nodes, int root)
{
var closest = new ClosestNode();
var visited = new List <bool>();
for (var i = 0; i < nodes.Count; i++)
{
visited.Add(i == root); // true if root, else false (not visited)
}
//Debug.Assert(visited[root], nameof(visited) + "[root] == true"); // assert that root is true.
var currentLevel = new Queue <int>();
currentLevel.Enqueue(root);
var distance = 0;
while (distance <= MAX_DISTANCE_BEFORE_INVALID && closest.Distance == INVALID)
{
var nextLevel = new Queue <int>();
var levelResults = new List <ClosestNode>();
while (currentLevel.Any())
{
var current = currentLevel.Dequeue();
if (nodes[current].IsBlack)
{
var cn = new ClosestNode {
Node = current, Distance = distance
};
levelResults.Add(cn);
}
foreach (var n in nodes[current].Neighbors)
{
if (visited[n])
{
continue;
}
visited[n] = true;
nextLevel.Enqueue(n);
}
}
++distance;
currentLevel = nextLevel;
foreach (var res in levelResults)
{
if (res.Distance < closest.Distance || (res.Distance == closest.Distance && res.Node < closest.Node) ||
closest.Distance == INVALID)
{
closest = res;
}
}
}
return(closest);
}
static void Main(string[] args)
{
string line = Console.ReadLine();
var splitLine = line?.Split(' ');
int n = Convert.ToInt32(splitLine?[0]); // broj čvorova [1, 10^5]
int e = Convert.ToInt32(splitLine?[1]); // broj bridova <= 2.5 * n
var nodes = new List <Node>();
// N čvovora w/ tip čvora t = {0, 1}, 1 if black
for (int i = 0; i < n; i++)
{
int t = Convert.ToInt32(Console.ReadLine());
nodes.Add(new Node(i, t));
}
// s & d predstavljaju indekse čvorova
// između kojih postoji brid u neusmjerenom grafu
for (int i = 0; i < e; i++)
{
line = Console.ReadLine();
splitLine = line?.Split(' ');
int s = Convert.ToInt32(splitLine?[0]);
int d = Convert.ToInt32(splitLine?[1]);
nodes[s].Neighbors.Add(d);
nodes[d].Neighbors.Add(s);
}
//Console.WriteLine();
for (int i = 0; i < n; i++)
{
var result = new ClosestNode {
Distance = DEFAULT_BLACK_NODE_DISTANCE, Node = i
}; // for black node
if (!nodes[i].IsBlack)
{
result = Search(nodes, i);
}
Console.WriteLine("{0} {1}", result.Node, result.Distance);
}
//Console.ReadLine();
}
