Initial commit for middle of the linked list in js

Author: nb-0310

Linked List/linked_list_middle.js

@@ -0,0 +1,57 @@
+/* 
+    Given the head of a singly linked list, return the middle node of the linked list.
+
+    If there are two middle nodes, return the second middle node.
+
+    Example 1:
+
+    Input: head = [1,2,3,4,5]
+    Output: [3,4,5]
+    Explanation: The middle node of the list is node 3.
+
+    Example 2:
+
+    Input: head = [1,2,3,4,5,6]
+    Output: [4,5,6]
+    Explanation: Since the list has two middle nodes with values 3 and 4, we return the second one.
+    
+    Constraints:
+
+    The number of nodes in the list is in the range [1, 100].
+    1 <= Node.val <= 100
+*/
+
+/**
+ * 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 {ListNode}
+ */
+var middleNode = function(head) {
+    let curr = head // Initialize the current node to the head
+    let size = 0 // Initialize the size to 0
+
+    // Traverse the Linked List
+    while (curr) { 
+        size += 1 // Keep track of the size of the Linked List
+        curr = curr.next
+    } // curr is equal to null at the end of the loop
+
+    let mid = Math.floor(size / 2) + 1 // Calculate the middle of the List
+    let count = 0 
+    curr = head // Reset current to head
+
+    // Traverse the Linked List
+    while (curr) {
+        count += 1 // Keep track of the number of visited nodes in the List
+
+        if (count === mid) return curr // When middle node found, return it
+
+        curr = curr.next
+    }
+};