Data commit

Task/Floyd-Warshall-algorithm/Ruby/floyd-warshall-algorithm.rb

@@ -0,0 +1,35 @@
+def floyd_warshall(n, edge)
+  dist = Array.new(n){|i| Array.new(n){|j| i==j ? 0 : Float::INFINITY}}
+  nxt = Array.new(n){Array.new(n)}
+  edge.each do |u,v,w|
+    dist[u-1][v-1] = w
+    nxt[u-1][v-1] = v-1
+  end
+
+  n.times do |k|
+    n.times do |i|
+      n.times do |j|
+        if dist[i][j] > dist[i][k] + dist[k][j]
+          dist[i][j] = dist[i][k] + dist[k][j]
+          nxt[i][j] = nxt[i][k]
+        end
+      end
+    end
+  end
+
+  puts "pair     dist    path"
+  n.times do |i|
+    n.times do |j|
+      next  if i==j
+      u = i
+      path = [u]
+      path << (u = nxt[u][j])  while u != j
+      path = path.map{|u| u+1}.join(" -> ")
+      puts "%d -> %d  %4d     %s" % [i+1, j+1, dist[i][j], path]
+    end
+  end
+end
+
+n = 4
+edge = [[1, 3, -2], [2, 1, 4], [2, 3, 3], [3, 4, 2], [4, 2, -1]]
+floyd_warshall(n, edge)