Add solution #323

Author: JoshCrozier

README.md

@@ -311,6 +311,7 @@
 320|[Generalized Abbreviation](./solutions/0320-generalized-abbreviation.js)|Medium|
 321|[Create Maximum Number](./solutions/0321-create-maximum-number.js)|Hard|
 322|[Coin Change](./solutions/0322-coin-change.js)|Medium|
+323|[Number of Connected Components in an Undirected Graph](./solutions/0323-number-of-connected-components-in-an-undirected-graph.js)|Medium|
 324|[Wiggle Sort II](./solutions/0324-wiggle-sort-ii.js)|Medium|
 326|[Power of Three](./solutions/0326-power-of-three.js)|Easy|
 327|[Count of Range Sum](./solutions/0327-count-of-range-sum.js)|Hard|

solutions/0323-number-of-connected-components-in-an-undirected-graph.js

@@ -0,0 +1,42 @@
+/**
+ * 323. Number of Connected Components in an Undirected Graph
+ * https://leetcode.com/problems/number-of-connected-components-in-an-undirected-graph/
+ * Difficulty: Medium
+ *
+ * You have a graph of n nodes. You are given an integer n and an array edges where
+ * edges[i] = [ai, bi] indicates that there is an edge between ai and bi in the graph.
+ *
+ * Return the number of connected components in the graph.
+ */
+
+/**
+ * @param {number} n
+ * @param {number[][]} edges
+ * @return {number}
+ */
+var countComponents = function(n, edges) {
+  const parent = new Array(n).fill().map((_, i) => i);
+  let components = n;
+
+  for (const [node1, node2] of edges) {
+    union(node1, node2);
+  }
+
+  return components;
+
+  function find(node) {
+    if (parent[node] !== node) {
+      parent[node] = find(parent[node]);
+    }
+    return parent[node];
+  }
+
+  function union(node1, node2) {
+    const root1 = find(node1);
+    const root2 = find(node2);
+    if (root1 !== root2) {
+      parent[root1] = root2;
+      components--;
+    }
+  }
+};