[Sync Iteration] go/linked-list/1

solutions/go/linked-list/1/linked_list.go

@@ -0,0 +1,120 @@
+package linkedlist
+
+import "errors"
+
+// Define List and Node types here.
+// Note: The tests expect Node type to include an exported field with name Value to pass.
+type Node struct {
+	Value any
+	prev  *Node
+	next  *Node
+}
+
+type List struct {
+	first *Node
+	last  *Node
+}
+
+func NewList(elements ...any) *List {
+	if len(elements) == 0 {
+		return &List{}
+	}
+
+	n := &Node{Value: elements[0]}
+
+	curr := n
+
+	for _, v := range elements[1:] {
+		curr.next = &Node{Value: v, prev: curr}
+		curr = curr.next
+	}
+
+	return &List{n, curr}
+}
+
+func (n *Node) Next() *Node {
+	return n.next
+}
+
+func (n *Node) Prev() *Node {
+	return n.prev
+}
+
+func (l *List) Unshift(v any) {
+	if l.first == nil {
+		l.first = &Node{Value: v}
+		l.last = l.first
+		return
+	}
+
+	l.first.prev = &Node{Value: v, next: l.first}
+	l.first = l.first.prev
+}
+
+func (l *List) Push(v any) {
+	if l.first == nil {
+		l.first = &Node{Value: v}
+		l.last = l.first
+		return
+	}
+
+	l.last.next = &Node{Value: v, prev: l.last}
+	l.last = l.last.next
+}
+
+func (l *List) Shift() (any, error) {
+	if l.first == nil {
+		return nil, errors.New("")
+	}
+
+	v := l.first.Value
+
+	// Only 1 node
+	if l.first.next == nil {
+		l.first, l.last = nil, nil
+	} else {
+		l.first = l.first.next
+		l.first.prev = nil
+	}
+
+	return v, nil
+}
+
+func (l *List) Pop() (any, error) {
+	if l.last == nil {
+		return nil, errors.New("")
+	}
+
+	v := l.last.Value
+
+	if l.first.next == nil {
+		l.first, l.last = nil, nil
+	} else {
+		l.last = l.last.prev
+		l.last.next = nil
+	}
+
+	return v, nil
+}
+
+func (l *List) Reverse() {
+	if l.first == nil {
+		return
+	}
+
+	l.first, l.last = l.last, l.first
+
+	n := l.last
+	for n != nil {
+		n.next, n.prev = n.prev, n.next
+		n = n.prev
+	}
+}
+
+func (l *List) First() *Node {
+	return l.first
+}
+
+func (l *List) Last() *Node {
+	return l.last
+}