feat: 143. Reorder List

Author: gwbaik9717

reorder-list/gwbaik9717.js

@@ -0,0 +1,46 @@
+// Time complexity: O(n)
+// Space complexity: O(n)
+
+/**
+ * Definition for singly-linked list.
+ * function ListNode(val, next) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.next = (next===undefined ? null : next)
+ * }
+ */
+/**
+ * @param {ListNode} head
+ * @return {void} Do not return anything, modify head in-place instead.
+ */
+var reorderList = function (head) {
+  const nodes = [];
+  let n = 0;
+
+  {
+    let current = head;
+    while (current) {
+      n++;
+      nodes.push(current);
+      current = current.next;
+    }
+  }
+
+  const answer = head;
+
+  {
+    let current = answer;
+    for (let i = 1; i < n; i++) {
+      if (i % 2 !== 0) {
+        current.next = nodes.at(n - Math.ceil(i / 2));
+      } else {
+        current.next = nodes.at(i / 2);
+      }
+
+      current = current.next;
+    }
+
+    current.next = null;
+  }
+
+  return answer;
+};