feat(Linked-List): ✨解决143

Author: descire

Linked-List/143/solution1.js

@@ -0,0 +1,68 @@
+/**
+ * https://leetcode-cn.com/problems/reorder-list/
+ * 
+ * 143. 重排链表
+ * 
+ * Medium
+ * 
+ * 92ms 97.62%
+ * 
+ * 40.7mb 83.33%
+ */
+const reorderList = head => {
+  if (!head || !head.next) {
+    return head;
+  }
+
+  // 寻找列表的中间值
+  let slow = head;
+  let fast = head;
+
+  while (fast && fast.next) {
+    fast = fast.next.next;
+    slow = slow.next;
+  }
+
+  // 翻转后半段
+  const secondHalf = slow.next;
+  slow.next = null;
+
+  let newSecondHalf = reverseLinkedList(secondHalf);
+
+  // 合并
+  let currentHead = head;
+  while (currentHead && newSecondHalf) {
+    const x = currentHead.next;
+    const y = newSecondHalf.next;
+    currentHead.next = newSecondHalf;
+    newSecondHalf.next = x;
+    currentHead = x;
+    newSecondHalf = y;
+  }
+}
+/**
+ * 1 -> 2 -> 3 -> 4 -> 5
+ * 一、
+ * head: 1
+ * nextNode: 2 -> 3 -> 4 -> 5
+ * 
+ * 二、
+ * head: 2 -> 1
+ * nextNode: 3 -> 4 -> 5
+ */
+function reverseLinkedList(head) {
+  if (!head || !head.next) {
+    return head;
+  }
+
+  let nextNode = head.next;
+  head.next = null;
+  while (nextNode) {
+    const temp = nextNode.next;
+    nextNode.next = head;
+    head = nextNode;
+    nextNode = temp;
+  }
+
+  return head;
+}