graph valid tree solution

Author: hyer0705

graph-valid-tree/hyer0705.ts

@@ -0,0 +1,39 @@
+// Time Complexity: O(n)
+// Space Complexity: O(n)
+export class Solution {
+  /**
+   * @param n: An integer
+   * @param edges: a list of undirected edges
+   * @return: true if it's a valid tree, or false
+   */
+  validTree(n: number, edges: number[][]): boolean {
+    if (n === 0) return true;
+    if (edges.length !== n - 1) return false;
+
+    const graph: number[][] = Array.from({ length: n }, () => []);
+
+    for (const [s, e] of edges) {
+      graph[s].push(e);
+      graph[e].push(s);
+    }
+
+    const visited = new Set<number>();
+
+    const queue = [0];
+    visited.add(0);
+
+    let pointer = 0;
+    while (pointer < queue.length) {
+      const currentNode = queue[pointer++];
+
+      for (const nextNode of graph[currentNode]) {
+        if (!visited.has(nextNode)) {
+          queue.push(nextNode);
+          visited.add(nextNode);
+        }
+      }
+    }
+
+    return visited.size === n;
+  }
+}