Feat: 261. Graph Valid Tree

Author: HC-kang

graph-valid-tree/HC-kang.ts

@@ -0,0 +1,33 @@
+/**
+ * https://leetcode.com/problems/graph-valid-tree
+ * T.C. O(n)
+ * S.C. O(n)
+ */
+function validTree(n: number, edges: number[][]): boolean {
+  if (edges.length !== n - 1) return false;
+
+  const parent = Array.from({ length: n }, (_, i) => i);
+
+  // find and compress path
+  function find(x: number): number {
+    if (parent[x] !== x) {
+      parent[x] = find(parent[x]);
+    }
+    return parent[x];
+  }
+
+  // union two sets and check if they have the same root
+  function union(x: number, y: number): boolean {
+    const rootX = find(x);
+    const rootY = find(y);
+    if (rootX === rootY) return false;
+    parent[rootX] = rootY;
+    return true;
+  }
+
+  for (const [x, y] of edges) {
+    if (!union(x, y)) return false;
+  }
+
+  return true;
+}