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package main
import "fmt"
/* v is the value of node; next is the pointer to next node */
type node struct {
v int
next *node
}
/* first node, called head. It points from first node to last node */
var head *node = nil
func (l *node) pushFront(val int) *node {
/* if there's no nodes, head points to l (first node) */
if head == nil {
l.v = val
l.next = nil
head = l
return l
} else {
/* create a new node equals to head */
nnode := new(node)
nnode = head
/* create a second node with new value and `next -> nnode`
* is this way, nnode2 is before nnode
*/
nnode2 := &node {
v: val,
next: nnode,
}
/* now head is equals nnode2 */
head = nnode2
return head
}
}
func (l *node) pushBack(val int) *node {
/* if there's no nodes, head points to l (first node) */
if head == nil {
l.v = val
l.next = nil
head = l
return l
} else {
/* read all list to last node */
for l.next != nil {
l = l.next
}
/* allocate a new portion of memory */
l.next = new(node)
l.next.v = val
l.next.next = nil
return l
}
}
func (l *node) popFront() *node {
if head == nil {
return head
}
/* create a new node equals to first node pointed by head */
cpnode := new(node)
cpnode = head.next
/* now head is equals cpnode (second node) */
head = cpnode
return head
}
func (l *node) popBack() *node {
if head == nil {
return head
}
/* create a new node equals to head */
cpnode := new(node)
cpnode = head
/* read list to the penultimate node */
for cpnode.next.next != nil {
cpnode = cpnode.next
}
/* the penultimate node points to null. In this way the last node is deleted */
cpnode.next = nil
return head
}
func main() {
lista := new(node)
lista.pushBack(25).pushBack(24).pushBack(32) /* lista: 25 24 32 */
lista.pushBack(56) /* lista: 25 24 32 56 */
lista.pushFront(36) /* lista: 36 25 24 32 56 */
lista.popFront() /* lista: 25 24 32 56 */
lista.popBack() /* lista: 25 24 32 */
/* read the list until head is not nil */
for head != nil {
fmt.Printf("%d ",head.v)
head = head.next /*head points to next node */
}
}