Improved Node.toString()

src/main/kotlin/com_github_leetcode/random/Node.kt

@@ -1,7 +1,5 @@
 package com_github_leetcode.random
 
-import java.util.StringJoiner
-
 class Node {
     var `val`: Int
     var next: Node? = null
@@ -12,33 +10,38 @@ class Node {
     }
 
     override fun toString(): String {
-        val result = StringJoiner(",", "[", "]")
-        val result2 = StringJoiner(",", "[", "]")
-        result2.add(`val`.toString())
+        val result = StringBuilder()
+        result.append("[")
+        result.append("[")
+        result.append(`val`)
+        result.append(",")
         if (random == null) {
-            result2.add("null")
+            result.append("null")
         } else {
-            result2.add(random!!.`val`.toString())
+            result.append(random!!.`val`)
         }
-        result.add(result2.toString())
+        result.append("]")
         var curr = next
         while (curr != null) {
-            val result3 = StringJoiner(",", "[", "]")
-            result3.add(curr.`val`.toString())
+            result.append(",")
+            result.append("[")
+            result.append(curr.`val`)
+            result.append(",")
             if (curr.random == null) {
-                result3.add("null")
+                result.append("null")
             } else {
                 var randomIndex = 0
-                var curr2: Node? = this
-                while (curr2!!.next != null && curr2 !== curr.random) {
-                    randomIndex += 1
-                    curr2 = curr2.next
+                var indexFinder: Node? = this
+                while (indexFinder!!.next != null && indexFinder !== curr.random) {
+                    randomIndex++
+                    indexFinder = indexFinder.next
                 }
-                result3.add(randomIndex.toString())
+                result.append(randomIndex)
             }
-            result.add(result3.toString())
+            result.append("]")
             curr = curr.next
         }
+        result.append("]")
         return result.toString()
     }
 }

src/main/kotlin/g0101_0200/s0133_clone_graph/Solution.kt

@@ -1,9 +1,9 @@
 package g0101_0200.s0133_clone_graph
 
 // #Medium #Hash_Table #Depth_First_Search #Breadth_First_Search #Graph #Udemy_Graph
-// #Top_Interview_150_Graph_General #2022_10_09_Time_351_ms_(60.91%)_Space_37.1_MB_(70.56%)
+// #Top_Interview_150_Graph_General #2025_08_03_Time_133_ms_(88.96%)_Space_43.11_MB_(67.94%)
 
-import com_github_leetcode.neighbors.Node
+import com_github_leetcode.Node
 
 /*
  * Definition for a Node.
@@ -24,11 +24,10 @@ class Solution {
         }
         val newNode = Node(node.`val`)
         processedNodes[node] = newNode
-        newNode.neighbors = ArrayList()
         for (neighbor in node.neighbors) {
-            val clonedNeighbor: Node? = cloneGraph(neighbor, processedNodes)
+            val clonedNeighbor = cloneGraph(neighbor, processedNodes)
             if (clonedNeighbor != null) {
-                newNode.neighbors.add(clonedNeighbor)
+                (newNode.neighbors as ArrayList).add(clonedNeighbor)
             }
         }
         return newNode

src/test/kotlin/com_github_leetcode/NodeTest.kt

@@ -5,13 +5,6 @@ import org.hamcrest.MatcherAssert.assertThat
 import org.junit.jupiter.api.Test
 
 internal class NodeTest {
-    @Test
-    fun constructor() {
-        val node = Node()
-        assertThat(node.`val`, equalTo(0))
-        assertThat(node.toString(), equalTo("[]"))
-    }
-
     @Test
     fun constructor2() {
         val node = Node(1)

src/test/kotlin/g0101_0200/s0133_clone_graph/SolutionTest.kt

@@ -1,6 +1,6 @@
 package g0101_0200.s0133_clone_graph
 
-import com_github_leetcode.neighbors.Node
+import com_github_leetcode.Node
 import org.hamcrest.CoreMatchers.equalTo
 import org.hamcrest.MatcherAssert.assertThat
 import org.junit.jupiter.api.Test