add

5.leetcode/src/com/fanxb/common/Q138.java

@@ -0,0 +1,46 @@
+package com.fanxb.common;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * TODO
+ *
+ * @author FleyX
+ * @date 2022/3/3 22:35
+ */
+public class Q138 {
+    private static class Node {
+        int val;
+        Node next;
+        Node random;
+
+        public Node(int val) {
+            this.val = val;
+            this.next = null;
+            this.random = null;
+        }
+    }
+
+    public Node copyRandomList(Node head) {
+        //老节点和新节点的对应关系
+        Map<Node, Node> oldNewMap = new HashMap<>();
+        //建立虚拟头节点便于处理
+        Node res = new Node(0), tempNew = res, tempOld = head;
+        while (tempOld != null) {
+            tempNew.next = new Node(tempOld.val);
+            tempNew = tempNew.next;
+            //旧节点和新节点一一对应
+            oldNewMap.put(tempOld, tempNew);
+            tempOld = tempOld.next;
+        }
+        //再次便利将random关系处理好
+        while (head != null) {
+            if (head.random != null) {
+                oldNewMap.get(head).random = oldNewMap.get(head.random);
+            }
+            head = head.next;
+        }
+        return res.next;
+    }
+}