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| 1 | +package main |
| 2 | + |
| 3 | +import "fmt" |
| 4 | + |
| 5 | +/* v is the value of node; next is the pointer to next node */ |
| 6 | +type node struct { |
| 7 | + v int |
| 8 | + next *node |
| 9 | +} |
| 10 | + |
| 11 | +/* first node, called head. It points from first node to last node */ |
| 12 | +var head *node = nil |
| 13 | + |
| 14 | +func (l *node) pushFront(val int) *node { |
| 15 | + /* if there's no nodes, head points to l (first node) */ |
| 16 | + if head == nil { |
| 17 | + l.v = val |
| 18 | + l.next = nil |
| 19 | + head = l |
| 20 | + return l |
| 21 | + } else { |
| 22 | + /* create a new node equals to head */ |
| 23 | + nnode := new(node) |
| 24 | + nnode = head |
| 25 | + /* create a second node with new value and `next -> nnode` |
| 26 | + * is this way, nnode2 is before nnode |
| 27 | + */ |
| 28 | + nnode2 := &node { |
| 29 | + v: val, |
| 30 | + next: nnode, |
| 31 | + } |
| 32 | + /* now head is equals nnode2 */ |
| 33 | + head = nnode2 |
| 34 | + return head |
| 35 | + } |
| 36 | +} |
| 37 | + |
| 38 | +func (l *node) pushBack(val int) *node { |
| 39 | + /* if there's no nodes, head points to l (first node) */ |
| 40 | + if head == nil { |
| 41 | + l.v = val |
| 42 | + l.next = nil |
| 43 | + head = l |
| 44 | + return l |
| 45 | + } else { |
| 46 | + /* read all list to last node */ |
| 47 | + for l.next != nil { |
| 48 | + l = l.next |
| 49 | + } |
| 50 | + /* allocate a new portion of memory */ |
| 51 | + l.next = new(node) |
| 52 | + l.next.v = val |
| 53 | + l.next.next = nil |
| 54 | + return l |
| 55 | + } |
| 56 | +} |
| 57 | + |
| 58 | +func (l *node) popFront() *node { |
| 59 | + if head == nil { |
| 60 | + return head |
| 61 | + } |
| 62 | + /* create a new node equals to first node pointed by head */ |
| 63 | + cpnode := new(node) |
| 64 | + cpnode = head.next |
| 65 | + |
| 66 | + /* now head is equals cpnode (second node) */ |
| 67 | + head = cpnode |
| 68 | + |
| 69 | + return head |
| 70 | +} |
| 71 | + |
| 72 | +func (l *node) popBack() *node { |
| 73 | + if head == nil { |
| 74 | + return head |
| 75 | + } |
| 76 | + /* create a new node equals to head */ |
| 77 | + cpnode := new(node) |
| 78 | + cpnode = head |
| 79 | + |
| 80 | + /* read list to the penultimate node */ |
| 81 | + for cpnode.next.next != nil { |
| 82 | + cpnode = cpnode.next |
| 83 | + } |
| 84 | + /* the penultimate node points to null. In this way the last node is deleted */ |
| 85 | + cpnode.next = nil |
| 86 | + return head |
| 87 | +} |
| 88 | + |
| 89 | +func main() { |
| 90 | + lista := new(node) |
| 91 | + lista.pushBack(25).pushBack(24).pushBack(32) /* lista: 25 24 32 */ |
| 92 | + lista.pushBack(56) /* lista: 25 24 32 56 */ |
| 93 | + lista.pushFront(36) /* lista: 36 25 24 32 56 */ |
| 94 | + lista.popFront() /* lista: 25 24 32 56 */ |
| 95 | + lista.popBack() /* lista: 25 24 32 */ |
| 96 | + |
| 97 | + /* read the list until head is not nil */ |
| 98 | + for head != nil { |
| 99 | + fmt.Printf("%d ",head.v) |
| 100 | + head = head.next /*head points to next node */ |
| 101 | + } |
| 102 | +} |
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