bfs shortest reach problem from hackerrank.

Author: deepakhb2

Interview-Questions/bfs_shortest_reach.rb

@@ -0,0 +1,57 @@
+=begin
+
+https://www.hackerrank.com/challenges/bfsshortreach/problem
+
+Output: 6 6 6 6 12 6 12 6 12 12 6 6 6 6 6 12 12 6 6 6 6 12 6 12 6 12 6 12 12 12 12 6 12 12 6 12 12 6 12 6 12 6 12 12 6 6 12 6 6 6 6 12 12 12 12 6 6 6 12 6 6 12 12 12 12 12 12 6 6
+=end
+require 'pry'
+
+def bfs(n, m, edges, s)
+  adj_list = {}
+  dist = {}
+  edges.each do |e|
+    if(adj_list[e[0]])
+      adj_list[e[0]][e[1]] = 6
+    else
+      adj_list[e[0]] = {e[1] => 6}
+    end
+    if(adj_list[e[1]])
+      adj_list[e[1]][e[0]] = 6
+    else
+      adj_list[e[1]] = {e[0] => 6}
+    end
+  end
+
+  queue = [s]
+  dist[s] = 0
+  while(!queue.empty?)
+    node = queue.shift
+    if(adj_list[node])
+      adj_list[node].each do |neigh, val|
+        if(!dist[neigh])
+          queue.push(neigh) 
+          dist[neigh] = dist[node] + val
+        end
+      end
+    end
+  end
+  (1..n).to_a.each do |node|
+    unless(dist[node])
+      dist[node] = -1
+    end
+  end
+  dist.delete(s)
+  return dist.sort.collect(&:last)
+end
+
+n = 70
+m = 1988
+s = 16
+edges = []
+File.open("bfs_shortest_reach_input.txt") do |file|
+  file.each do |line|
+    line = line.gsub(/\n/,'')
+    edges << line.split(" ").collect(&:to_i)
+  end
+end
+p bfs(n, m, edges, s)