- Graph Valid Tree #262

Author: ayosecu

graph-valid-tree/ayosecu.py

@@ -0,0 +1,42 @@
+from collections import deque, defaultdict
+
+class Solution:
+    """
+        - Time Complexity: O(n + e), e = len(edges)
+        - Space Complexity: O(n), The size of dictionary
+    """
+    def validTree(self, n, edges):
+        # The number of edges must be "n - 1"
+        if len(edges) != n - 1:
+            return False
+
+        dic = defaultdict(list)
+        for u, v in edges:
+            dic[u].append(v)
+            dic[v].append(u)
+
+        # BFS for visiting all nodes
+        visited = set()
+        dq = deque([0])
+
+        while dq:
+            node = dq.popleft()
+            if node in visited:
+                continue
+            visited.add(node)
+            for next in dic[node]:
+                if next not in visited:
+                    dq.append(next)
+
+        # Check all nodes were visited
+        return len(visited) == n
+
+tc = [
+        (5, [[0, 1], [0, 2], [0, 3], [1, 4]], True),
+        (5, [[0, 1], [1, 2], [2, 3], [1, 3], [1, 4]], False)
+]
+
+sol = Solution()
+for i, (n, edges, e) in enumerate(tc, 1):
+    r = sol.validTree(n, edges)
+    print(f"TC {i} is Passed!" if r == e else f"TC {i} is Failed! - Expected: {e}, Result: {r}")