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lib/linked-list.js

@@ -17,87 +17,180 @@ class LinkedList {
     /*
     method to add a new node with the specific data value in the linked list
     insert the new node at the beginning of the linked list
-    Time Complexity: ?
-    Space Complexity: ?
+    Time Complexity: O(1)
+    Space Complexity: O(1)
     */
     addFirst(value) {
-        throw new Error("This method hasn't been implemented yet!");
+        const addNode = new Node(value) // create Node object
+        addNode.next = this.#head // pointer 'next' is assigned to current head pointer
+        this.#head = addNode; //Head is now equal to new node
+        let current = this.#head //better name for head
+        return current
     }
 
     /*
     method to find if the linked list contains a node with specified value
     returns true if found, false otherwise
-    Time Complexity: ?
-    Space Complexity: ?
+    Time Complexity: O(n)
+    Space Complexity: O(1)
     */
     search(value) {
-        throw new Error("This method hasn't been implemented yet!");
+
+        let current = this.#head
+        if (!current) return false
+        if(current.value === value) return true
+
+        while(current != null) {
+            if(current.value === value) {
+                return true;
+            }else {
+                current = current.next;
+        }
     }
+    return false; 
+}
 
     /*
     method to return the max value in the linked list
     returns the data value and not the node
-    Time Complexity: ?
-    Space Complexity: ?
+    Time Complexity: O(n)
+    Space Complexity: O(1)
     */
     findMax() {
-        throw new Error("This method hasn't been implemented yet!");
+        let maxNum = 0 
+
+        let current = this.#head
+        if (current == null) return null
+
+        while(current != null) {
+            if(current.value > maxNum) {
+                maxNum = current.value
+            }else {
+                current = current.next
+            }
+        }
+        return maxNum
     }
     /*
     method to return the min value in the linked list
     returns the data value and not the node
-    Time Complexity: ?
-    Space Complexity: ?
+    Time Complexity: O(n)
+    Space Complexity: O(1)
      */
     findMin() {
-        throw new Error("This method hasn't been implemented yet!");
+        let current = this.#head
+        if (current == null) return null;
+
+        let minNum = current.value;
+        while(current != null) {
+            if(current.value < minNum) {
+                minNum = current.value
+            }else {
+                current = current.next
+            }
+        }
+        return minNum
     }
 
     /*
     method that returns the length of the singly linked list
-    Time Complexity: ?
-    Space Complexity: ?
+    Time Complexity: O(n)
+    Space Complexity: O(1)
      */
     length() {
-        throw new Error("This method hasn't been implemented yet!");
+        let current = this.#head
+        if (current == null) return 0;
+        let length = 0
+
+        while(current != null) {
+            length ++;
+            current = current.next;
+        }
+        return length  
     }
 
     /*
     method that returns the value at a given index in the linked list
     index count starts at 0
     returns nil if there are fewer nodes in the linked list than the index value
-    Time Complexity: ?
-    Space Complexity: ?
+    Time Complexity: O(n)
+    Space Complexity: O(1)
      */
     getAtIndex(index) {
-        throw new Error("This method hasn't been implemented yet!");
+        let current = this.#head
+        let count = 0
+        if (current == null) return null
+        while(count != null && count < index) {
+            count++    
+            current = current.next
+        }   
+        return current.value
     }
 
     /*
     method to print all the values in the linked list
-    Time Complexity: ?
-    Space Complexity: ?
+    Time Complexity: O(n) * O(k) -- i don't know! You have to first traverse the linked list and THEN an array
+    Space Complexity: ???
     */
     visit() {
-        throw new Error("This method hasn't been implemented yet!");
+        let current = this.#head
+        if (current == null) return null;
+        let printJob = [];
+
+        while(current != null) {
+            printJob.push(current.value);
+            current = current.next;
+        }
+        console.log(printJob.join(' ')); //print array as string
     }
     /*
     method to delete the first node found with specified value
-    Time Complexity: ?
-    Space Complexity: ?
+    Time Complexity: O(n)
+    Space Complexity: O(1)
     */
     delete(value) {
-        throw new Error("This method hasn't been implemented yet!");
-    }
-
+        let current = this.#head;
+        let previous = null;
+
+        if (current === null) return null; // empty list returns null
+
+        if (current.value === value) {
+            this.#head = current.next; //in case first value is value to be deleted
+            return
+        } 
+
+        while (current != null) {
+            if (current.value == value) {
+                previous.next = current.next; 
+                return
+            }
+            previous = current
+            current = current.next;
+        }
+        return "Value not found!";  
+    }    
+
     /*
     method to reverse the singly linked list
     note: the nodes should be moved and not just the values in the nodes
-    Time Complexity: ?
-    Space Complexity: ?
+    Time Complexity: O(n)
+    Space Complexity: O(1)
     */
     reverse() {
-        throw new Error("This method hasn't been implemented yet!");
+        let current = this.#head;
+        let previous = null;
+        let next = null;
+
+        if (current === null) return null;
+
+        while(current != null) {
+            next = current.next; // reassign current.next before reassigning it to previous
+            current.next = previous;
+            previous = current; 
+            current = next;
+        }
+        this.#head = previous 
+        return
     }
 
     // Advanced Exercises
@@ -142,7 +235,9 @@ class LinkedList {
     Space Complexity: ?
     */
     getFirst() {
-        throw new Error("This method hasn't been implemented yet!");
+        let current = this.#head;
+        if (current == null) return null
+        return current.value
     }
 
     /*