문제 추가

Author: jdalma

clone-graph/jdalma.kt

@@ -0,0 +1,94 @@
+package leetcode_study
+
+import io.kotest.matchers.shouldBe
+import org.junit.jupiter.api.Test
+import java.lang.RuntimeException
+import java.util.ArrayDeque
+import java.util.Queue
+
+class `clone-graph` {
+
+    data class Node(var `val`: Int) {
+        var neighbors: ArrayList<Node?> = ArrayList()
+    }
+
+    fun cloneGraph(node: Node?): Node? {
+        if (node == null) return null
+
+        return usingBFS(node)
+    }
+
+    /**
+     * TC: O(n), SC: O(n)
+     */
+    private fun usingDFS(node: Node): Node {
+
+        fun dfs(node: Node, nodes: MutableMap<Int, Node>): Node {
+            nodes[node.`val`]?.let {
+                return it
+            }
+            val copy = Node(node.`val`)
+            nodes[node.`val`] = copy
+
+            for (near in node.neighbors.filterNotNull()) {
+                copy.neighbors.add(dfs(near, nodes))
+            }
+
+            return copy
+        }
+        return dfs(node, mutableMapOf())
+    }
+
+    /**
+     * TC: O(n), SC: O(n)
+     */
+    private fun usingBFS(node: Node): Node {
+        val nodes = mutableMapOf<Int, Node>().apply {
+            this[node.`val`] = Node(node.`val`)
+        }
+        val queue: Queue<Node> = ArrayDeque<Node>().apply {
+            this.offer(node)
+        }
+
+        while (queue.isNotEmpty()) {
+            val now = queue.poll()
+            val copy = nodes[now.`val`] ?: throw RuntimeException()
+            for (near in now.neighbors.filterNotNull()) {
+                if (!nodes.containsKey(near.`val`)) {
+                    nodes[near.`val`] = Node(near.`val`)
+                    queue.add(near)
+                }
+                copy.neighbors.add(nodes[near.`val`])
+            }
+        }
+        return nodes[node.`val`] ?: Node(node.`val`)
+    }
+
+    private fun fixture(): Node {
+        val one = Node(1)
+        val two = Node(2)
+        val three = Node(3)
+        val four = Node(4)
+
+        one.neighbors.add(two)
+        one.neighbors.add(four)
+        two.neighbors.add(one)
+        two.neighbors.add(three)
+        three.neighbors.add(two)
+        three.neighbors.add(four)
+        four.neighbors.add(one)
+        four.neighbors.add(three)
+
+        return one
+    }
+
+    @Test
+    fun `입력받은 노드의 깊은 복사본을 반환한다`() {
+        val actualNode = fixture()
+        val expectNode = cloneGraph(actualNode)
+        actualNode shouldBe expectNode
+
+        actualNode.`val` = 9999
+        expectNode!!.`val` shouldBe 1
+    }
+}