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- avl tree: expose children and parent nodes, can be useful when extending structure to have access to these

Browse Source
pull/51/head
Emir Pasic 9 years ago
parent f480e9419a
commit 59734f8164
1 changed files with 51 additions and 51 deletions
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102
trees/avltree/avltree.go
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@ -19,18 +19,18 @@ func assertTreeImplementation() {
// Tree holds elements of the AVL tree.
type Tree struct {
Root *Node
size int
Comparator utils.Comparator
Root *Node // Root node
Comparator utils.Comparator // Key comparator
size int // Total number of keys in the tree
}
// Node is a single element within the tree
type Node struct {
Key interface{}
Value interface{}
c [2]*Node
p *Node
b int8
Key interface{}
Value interface{}
Parent *Node // Parent node
Children [2]*Node // Children nodes
b int8
}
// NewWith instantiates an AVL tree with the custom comparator.
@ -80,9 +80,9 @@ func (t *Tree) Get(key interface{}) (value interface{}, found bool) {
case cmp == 0:
return n.Value, true
case cmp < 0:
n = n.c[0]
n = n.Children[0]
case cmp > 0:
n = n.c[1]
n = n.Children[1]
}
}
return nil, false
@ -105,10 +105,10 @@ func (t *Tree) Floor(key interface{}) (floor *Node, found bool) {
case c == 0:
return n, true
case c < 0:
n = n.c[0]
n = n.Children[0]
case c > 0:
floor, found = n, true
n = n.c[1]
n = n.Children[1]
}
}
if found {
@ -135,9 +135,9 @@ func (t *Tree) Ceiling(key interface{}) (floor *Node, found bool) {
return n, true
case c < 0:
floor, found = n, true
n = n.c[0]
n = n.Children[0]
case c > 0:
n = n.c[1]
n = n.Children[1]
}
}
if found {
@ -154,7 +154,7 @@ func (t *Tree) Put(key interface{}, value interface{}) {
q := *qp
if q == nil {
t.size++
*qp = &Node{Key: key, Value: value, p: p}
*qp = &Node{Key: key, Value: value, Parent: p}
return true
}
@ -172,7 +172,7 @@ func (t *Tree) Put(key interface{}, value interface{}) {
}
a := (c + 1) / 2
var fix bool
fix = put(q, &q.c[a])
fix = put(q, &q.Children[a])
if fix {
return putFix(int8(c), qp)
}
@ -195,14 +195,14 @@ func (t *Tree) Remove(key interface{}) {
c := t.Comparator(key, q.Key)
if c == 0 {
t.size--
if q.c[1] == nil {
if q.c[0] != nil {
q.c[0].p = q.p
if q.Children[1] == nil {
if q.Children[0] != nil {
q.Children[0].Parent = q.Parent
}
*qp = q.c[0]
*qp = q.Children[0]
return true
}
fix := removeMin(&q.c[1], &q.Key, &q.Value)
fix := removeMin(&q.Children[1], &q.Key, &q.Value)
if fix {
return removeFix(-1, qp)
}
@ -215,7 +215,7 @@ func (t *Tree) Remove(key interface{}) {
c = 1
}
a := (c + 1) / 2
fix := remove(&q.c[a])
fix := remove(&q.Children[a])
if fix {
return removeFix(int8(-c), qp)
}
@ -227,16 +227,16 @@ func (t *Tree) Remove(key interface{}) {
func removeMin(qp **Node, minKey *interface{}, minVal *interface{}) bool {
q := *qp
if q.c[0] == nil {
if q.Children[0] == nil {
*minKey = q.Key
*minVal = q.Value
if q.c[1] != nil {
q.c[1].p = q.p
if q.Children[1] != nil {
q.Children[1].Parent = q.Parent
}
*qp = q.c[1]
*qp = q.Children[1]
return true
}
fix := removeMin(&q.c[0], minKey, minVal)
fix := removeMin(&q.Children[0], minKey, minVal)
if fix {
return removeFix(1, qp)
}
@ -255,7 +255,7 @@ func putFix(c int8, t **Node) bool {
return false
}
if s.c[(c+1)/2].b == c {
if s.Children[(c+1)/2].b == c {
s = singlerot(c, s)
} else {
s = doublerot(c, s)
@ -277,14 +277,14 @@ func removeFix(c int8, t **Node) bool {
}
a := (c + 1) / 2
if s.c[a].b == 0 {
if s.Children[a].b == 0 {
s = rotate(c, s)
s.b = -c
*t = s
return false
}
if s.c[a].b == c {
if s.Children[a].b == c {
s = singlerot(c, s)
} else {
s = doublerot(c, s)
@ -302,8 +302,8 @@ func singlerot(c int8, s *Node) *Node {
func doublerot(c int8, s *Node) *Node {
a := (c + 1) / 2
r := s.c[a]
s.c[a] = rotate(-c, s.c[a])
r := s.Children[a]
s.Children[a] = rotate(-c, s.Children[a])
p := rotate(c, s)
switch {
@ -324,14 +324,14 @@ func doublerot(c int8, s *Node) *Node {
func rotate(c int8, s *Node) *Node {
a := (c + 1) / 2
r := s.c[a]
s.c[a] = r.c[a^1]
if s.c[a] != nil {
s.c[a].p = s
r := s.Children[a]
s.Children[a] = r.Children[a^1]
if s.Children[a] != nil {
s.Children[a].Parent = s
}
r.c[a^1] = s
r.p = s.p
s.p = r
r.Children[a^1] = s
r.Parent = s.Parent
s.Parent = r
return r
}
@ -393,7 +393,7 @@ func (t *Tree) bottom(d int) *Node {
return nil
}
for c := n.c[d]; c != nil; c = n.c[d] {
for c := n.Children[d]; c != nil; c = n.Children[d] {
n = c
}
return n
@ -416,18 +416,18 @@ func (n *Node) walk1(a int) *Node {
return nil
}
if n.c[a] != nil {
n = n.c[a]
for n.c[a^1] != nil {
n = n.c[a^1]
if n.Children[a] != nil {
n = n.Children[a]
for n.Children[a^1] != nil {
n = n.Children[a^1]
}
return n
}
p := n.p
for p != nil && p.c[a] == n {
p := n.Parent
for p != nil && p.Children[a] == n {
n = p
p = p.p
p = p.Parent
}
return p
}
@ -446,14 +446,14 @@ func (n *Node) String() string {
}
func output(node *Node, prefix string, isTail bool, str *string) {
if node.c[0] != nil {
if node.Children[0] != nil {
newPrefix := prefix
if isTail {
newPrefix += "│ "
} else {
newPrefix += " "
}
output(node.c[0], newPrefix, false, str)
output(node.Children[0], newPrefix, false, str)
}
*str += prefix
if isTail {
@ -462,13 +462,13 @@ func output(node *Node, prefix string, isTail bool, str *string) {
*str += "┌── "
}
*str += node.String() + "\n"
if node.c[1] != nil {
if node.Children[1] != nil {
newPrefix := prefix
if isTail {
newPrefix += " "
} else {
newPrefix += "│ "
}
output(node.c[1], newPrefix, true, str)
output(node.Children[1], newPrefix, true, str)
}
}

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