Add kotlin/0261-graph-valid-tree.kt

Author: themlkang42

kotlin/0261-graph-valid-tree.kt

@@ -0,0 +1,29 @@
+class Solution {
+    private lateinit var adjList: Array<MutableList<Int>>
+    private val seen = mutableSetOf<Int>()
+
+    fun validTree(n: Int, edges: Array<IntArray>): Boolean {
+        if (edges.size != n-1) {
+            return false
+        }
+
+        adjList = Array(n) { mutableListOf() }
+        for (edge in edges) {
+            adjList[edge[0]].add(edge[1])
+            adjList[edge[1]].add(edge[0])
+        }
+        dfs(0)
+
+        return seen.size == n
+    }
+
+    private fun dfs(node: Int) {
+        if (seen.contains(node)) {
+            return
+        }
+        seen.add(node)
+        for (adj in adjList[node]) {
+            dfs(adj)
+        }
+    }
+}