Data update

Task/Floyd-Warshall-algorithm/Scala/floyd-warshall-algorithm.scala

@@ -0,0 +1,50 @@
+import java.lang.String.format;
+
+object FloydWarshall extends App {
+
+  val weights = Array(Array(1, 3, -2), Array(2, 1, 4), Array(2, 3, 3), Array(3, 4, 2), Array(4, 2, -1))
+  val numVertices = 4
+
+  floydWarshall(weights, numVertices)
+
+  def floydWarshall(weights: Array[Array[Int]], numVertices: Int): Unit = {
+
+    val dist = Array.fill(numVertices, numVertices)(Double.PositiveInfinity)
+    for (w <- weights)
+      dist(w(0) - 1)(w(1) - 1) = w(2)
+
+    val next = Array.ofDim[Int](numVertices, numVertices)
+    for (i <- 0 until numVertices; j <- 0 until numVertices if i != j)
+      next(i)(j) = j + 1
+
+    for {
+      k <- 0 until numVertices
+      i <- 0 until numVertices
+      j <- 0 until numVertices
+      if dist(i)(k) + dist(k)(j) < dist(i)(j)
+    } {
+      dist(i)(j) = dist(i)(k) + dist(k)(j)
+      next(i)(j) = next(i)(k)
+    }
+
+    printResult(dist, next)
+  }
+
+  def printResult(dist: Array[Array[Double]], next: Array[Array[Int]]): Unit = {
+    println("pair     dist    path")
+    for {
+      i <- 0 until next.length
+      j <- 0 until next.length if i != j
+    } {
+      var u = i + 1
+      val v = j + 1
+      var path = format("%d -> %d    %2d     %s", u, v,
+                            (dist(i)(j)).toInt, u);
+      while (u != v) {
+        u = next(u - 1)(v - 1)
+        path += s" -> $u"
+      }
+      println(path)
+    }
+  }
+}