19/09/01

zhangbo · zhangbo · commit 68541e45b52d · 2019-09-01T23:18:59.000+08:00
diff --git a/138.List.M-CopylistWithRandomPointer.js b/138.List.M-CopylistWithRandomPointer.js
@@ -0,0 +1,30 @@
+/**
+ * A linked list is given such that each node contains an additional random pointer which could point to any node in the list or null.
+ * Return a deep copy of the list.
+ */
+
+/**
+ * // Definition for a Node.
+ * function Node(val,next,random) {
+ *    this.val = val;
+ *    this.next = next;
+ *    this.random = random;
+ * };
+ */
+/**
+ * @param {Node} head
+ * @return {Node}
+ */
+var copyRandomList = function (head) {
+  const m = new Map()
+  function helper(node, m) {
+    if (!node) return null
+    if (m.has(node)) return m.get(node)
+    const n = new Node(node.val, null, null)
+    m.set(node, n)
+    n.next = helper(node.next, m)
+    n.random = helper(node.random, m)
+    return n
+  }
+  return helper(head, m)
+};
