547. Number of Provinces

Author: a-khakimov

leetcode-scala/src/main/scala/LeetCode75/Graphs_DFS/547. Number of Provinces.sc

@@ -0,0 +1,63 @@
+object Solution {
+
+  def dfs(graph: Map[Int, Set[Int]], start: Int, visited: Set[Int] = Set.empty): Set[Int] = {
+    if (visited.contains(start)) visited
+    else graph.getOrElse(start, Nil).foldLeft(visited + start)(
+      (acc, neighbor) => dfs(graph, neighbor, acc)
+    )
+  }
+
+  // stupid solution
+  def findCircleNum(isConnected: Array[Array[Int]]): Int = {
+    val graph = scala.collection.mutable.Map.empty[Int, Set[Int]]
+    val n = isConnected.length
+    var i = 0
+    while (i < n) {
+      var j = 0
+      while (j < n) {
+        if (isConnected(i)(j) == 1) {
+          graph.addOne(i, graph.get(i).toSet.flatten + j)
+        }
+        j += 1
+      }
+      i += 1
+    }
+
+    val circles = scala.collection.mutable.ArrayBuffer.empty[Set[Int]]
+    isConnected.indices.foreach(
+      i => if (!circles.exists(_.exists(_ == i))) circles.addOne(dfs(graph.toMap, i))
+    )
+
+    circles.size
+  }
+}
+
+object Solution2 {
+  def findCircleNum(isConnected: Array[Array[Int]]): Int = {
+    val n = isConnected.length
+    val visited = Array.fill(n)(false)
+
+    def dfs(city: Int): Unit = {
+      for (neighbor <- 0 until n) {
+        if (isConnected(city)(neighbor) == 1 && !visited(neighbor)) {
+          visited(neighbor) = true
+          dfs(neighbor)
+        }
+      }
+    }
+
+    var provinces = 0
+
+    for (i <- 0 until n) {
+      if (!visited(i)) {
+        provinces += 1
+        visited(i) = true
+        dfs(i)
+      }
+    }
+    provinces
+  }
+}
+
+Solution2.findCircleNum(Array(Array(1, 1, 0), Array(1, 1, 0), Array(0, 0, 1)))
+Solution2.findCircleNum(Array(Array(1, 0, 0), Array(0, 1, 0), Array(0, 0, 1)))