323 js countComponents

anthonysim · anthonysim · commit e91f8a83cb26 · 2022-07-06T16:42:03.000-07:00
diff --git a/javascript/323-countComponents.js b/javascript/323-countComponents.js
@@ -0,0 +1,38 @@
+function buildGraph(n, edges) {
+  const graph = Array.from({ length: n }, () => []);
+
+  for (let edge of edges) {
+    let [a, b] = edge;
+
+    if (!(a in graph)) graph[a] = [];
+    if (!(b in graph)) graph[b] = [];
+
+    graph[a].push(b);
+    graph[b].push(a);
+  }
+  return graph;
+}
+
+var countComponents = function (n, edges) {
+  const graph = buildGraph(n, edges);
+  let count = 0;
+  let visited = new Set();
+
+  function explore(graph, current, visited) {
+    if (visited.has(current.toString())) return;
+
+    visited.add(current.toString());
+
+    for (let neighbor of graph[current]) {
+      explore(graph, neighbor, visited);
+    }
+    return true;
+  }
+
+  for (let node in graph) {
+    if (explore(graph, node, visited)) {
+      count += 1;
+    }
+  }
+  return count;
+};
