Initial data commit

Task/Doubly-linked-list-Element-insertion/Go/doubly-linked-list-element-insertion.go

@@ -0,0 +1,55 @@
+package main
+
+import "fmt"
+
+type dlNode struct {
+    string
+    next, prev *dlNode
+}
+
+type dlList struct {
+    head, tail *dlNode
+}
+
+func (list *dlList) String() string {
+    if list.head == nil {
+        return fmt.Sprint(list.head)
+    }
+    r := "[" + list.head.string
+    for p := list.head.next; p != nil; p = p.next {
+        r += " " + p.string
+    }
+    return r + "]"
+}
+
+func (list *dlList) insertTail(node *dlNode) {
+    if list.tail == nil {
+        list.head = node
+    } else {
+        list.tail.next = node
+    }
+    node.next = nil
+    node.prev = list.tail
+    list.tail = node
+}
+
+func (list *dlList) insertAfter(existing, insert *dlNode) {
+    insert.prev = existing
+    insert.next = existing.next
+    existing.next.prev = insert
+    existing.next = insert
+    if existing == list.tail {
+        list.tail = insert
+    }
+}
+
+func main() {
+    dll := &dlList{}
+    fmt.Println(dll)
+    a := &dlNode{string: "A"}
+    dll.insertTail(a)
+    dll.insertTail(&dlNode{string: "B"})
+    fmt.Println(dll)
+    dll.insertAfter(a, &dlNode{string: "C"})
+    fmt.Println(dll)
+}