feat: 19. Remove Nth Node From End of List

Author: gwbaik9717

remove-nth-node-from-end-of-list/gwbaik9717.js

@@ -0,0 +1,50 @@
+// Time complexity: O(n)
+// Space complexity: O(1)
+
+/**
+ * Definition for singly-linked list.
+ * function ListNode(val, next) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.next = (next===undefined ? null : next)
+ * }
+ */
+/**
+ * @param {ListNode} head
+ * @param {number} n
+ * @return {ListNode}
+ */
+var removeNthFromEnd = function (head, n) {
+  const reverse = (head) => {
+    let next = null;
+    let current = head;
+
+    while (current) {
+      const temp = current.next;
+      current.next = next;
+      next = current;
+      current = temp;
+    }
+
+    return next;
+  };
+
+  // Reverse
+  let reversedHead = reverse(head);
+
+  if (n === 1) {
+    reversedHead = reversedHead.next;
+  } else {
+    let prev = null;
+    let current = reversedHead;
+
+    for (let i = 1; i < n; i++) {
+      prev = current;
+      current = current.next;
+    }
+
+    prev.next = current.next;
+  }
+
+  // Reverse Again
+  return reverse(reversedHead);
+};