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Merge pull request #2 from geniussportsgroup/develop
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Develop
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@lrleon
lrleon authored Sep 20, 2020
2 parents 485cb38 + e1d32b3 commit c249963
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Showing 2 changed files with 104 additions and 100 deletions.
78 changes: 41 additions & 37 deletions treaps.go
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
// Package Treap exports a ordered set of arbitrary keys implemented through treaps.
// A treap is a kind of balanced binary search tree where their operations are O(log n).
// A treap is a kind of balanced binary Search tree where their operations are O(log n).
package treaps

import (
Expand Down Expand Up @@ -43,8 +43,8 @@ type Treap struct {
less func(i1, i2 interface{}) bool
}

// swap two treaps in O(1)
func (tree *Treap) swap(rhs *Treap) {
// Swap two treaps in O(1)
func (tree *Treap) Swap(rhs *Treap) {
tree.seed, rhs.seed = rhs.seed, tree.seed
tree.randGenerator, rhs.randGenerator = rhs.randGenerator, tree.randGenerator
tree.rootPtr, rhs.rootPtr = rhs.rootPtr, tree.rootPtr
Expand Down Expand Up @@ -74,7 +74,7 @@ func NewTreap(less func(i1, i2 interface{}) bool) *Treap {
return New(time.Now().UTC().UnixNano(), less)
}

// Helper function that perform an exact topological copy of tree rooted by p
// Helper function that perform an exact topological Copy of tree rooted by p
func __copy(p *Node) *Node {

if p == nullNodePtr {
Expand All @@ -90,8 +90,8 @@ func __copy(p *Node) *Node {
}
}

// Get an exact copy of tree
func (tree *Treap) copy() *Treap {
// Get an exact Copy of tree
func (tree *Treap) Copy() *Treap {

ret := New(tree.seed, tree.less)
*ret.rootPtr = __copy(*tree.rootPtr)
Expand Down Expand Up @@ -120,7 +120,7 @@ func __topologicalEqual(t1, t2 *Node, less func(i1, i2 interface{}) bool) bool {
}

// Return true if tree is topologically equivalent to rhs
func (tree *Treap) topologicalEqual(rhs *Treap) bool {
func (tree *Treap) TopologicalEqual(rhs *Treap) bool {
return __topologicalEqual(*tree.rootPtr, *rhs.rootPtr, tree.less)
}

Expand Down Expand Up @@ -165,7 +165,7 @@ func __insertNode(root, p *Node, less func(i1, i2 interface{}) bool) *Node {

// Insert item into the tree. Return nil if key is already contained; otherwise
// returns the value of the just inserted item
func (tree *Treap) insert(item interface{}) interface{} {
func (tree *Treap) Insert(item interface{}) interface{} {

p := &Node{
key: item,
Expand All @@ -186,7 +186,7 @@ func (tree *Treap) insert(item interface{}) interface{} {

// Search in tree key. If key is found, then the value contained in the set is returned.
// Otherwise, the key was not found, nil value is returned
func (tree *Treap) search(key interface{}) interface{} {
func (tree *Treap) Search(key interface{}) interface{} {

root := *tree.rootPtr
for root != nullNodePtr {
Expand All @@ -207,7 +207,7 @@ func (tree *Treap) search(key interface{}) interface{} {
return root.key
}

// Helper function for searching a node and eventually insert it into the tree if it is not found
// Helper function for searching a node and eventually Insert it into the tree if it is not found
func __searchOrInsertNode(root **Node, p *Node, less func(i1, i2 interface{}) bool) *Node {

if *root == nullNodePtr {
Expand Down Expand Up @@ -242,7 +242,7 @@ func __searchOrInsertNode(root **Node, p *Node, less func(i1, i2 interface{}) bo

// Search in tree item. If it is found, then the pair (false, item-value) is returned.
// Otherwise, the item is inserted into the tree and the pair (true, item) is returned
func (tree *Treap) searchOrInsert(item interface{}) (bool, interface{}) {
func (tree *Treap) SearchOrInsert(item interface{}) (bool, interface{}) {

p := &Node{
key: item,
Expand Down Expand Up @@ -293,7 +293,7 @@ func __remove(rootPtr **Node, key interface{}, less func(i1, i2 interface{}) boo

// Remove key from the tree. Return the removed value if the removal was successful.
// Otherwise, the item was not found and the value nil is returned as signal of the failure
func (tree *Treap) remove(key interface{}) interface{} {
func (tree *Treap) Remove(key interface{}) interface{} {

retVal := __remove(tree.rootPtr, key, tree.less)
if retVal == nullNodePtr {
Expand All @@ -304,7 +304,7 @@ func (tree *Treap) remove(key interface{}) interface{} {
}

// Return the smallest item contained in the tree
func (tree *Treap) min() interface{} {
func (tree *Treap) Min() interface{} {

root := *tree.rootPtr
if root == nullNodePtr {
Expand All @@ -319,7 +319,7 @@ func (tree *Treap) min() interface{} {
}

// Return the greatest item contained in the tree
func (tree *Treap) max() interface{} {
func (tree *Treap) Max() interface{} {

root := *tree.rootPtr
if root == nullNodePtr {
Expand All @@ -334,7 +334,7 @@ func (tree *Treap) max() interface{} {
}

// Return in O(1) the number of keys contained in the tree
func (tree *Treap) size() int { return (*tree.rootPtr).count }
func (tree *Treap) Size() int { return (*tree.rootPtr).count }

// Helper function for splitting a tree according to key. The function returns two new trees.
// tsRoot contains all the keys less than key and tgRoot contains the keys greater or equal to
Expand Down Expand Up @@ -362,10 +362,10 @@ func __splitByKeyDup(root *Node, key interface{},
return tsRoot, tgRoot
}

// split tree in two trees tsTree and tgTres. tsTree contains all the keys of tree in
// [tree.min(), key> and tgTree contains those ones in [key, tree.max]. After completion,
// SplitByKey tree in two trees tsTree and tgTres. tsTree contains all the keys of tree in
// [tree.Min(), key> and tgTree contains those ones in [key, tree.Max]. After completion,
// tree becomes empty.
func (tree *Treap) split(key interface{}) (tsTree, tgTree *Treap) {
func (tree *Treap) SplitByKey(key interface{}) (tsTree, tgTree *Treap) {

tsTree = New(tree.seed, tree.less)
tgTree = New(tree.seed, tree.less)
Expand Down Expand Up @@ -403,18 +403,20 @@ func __joinExclusive(tsRootPtr, tgRootPtr **Node) *Node {

// join exclusive of tsTree with tgTree. Equivalent to append tgTree to tsTree.
// tgTree must be greater than tsTree. Panic is thrown if this condition is not met
func (tsTree *Treap) joinExclusive(tgTree *Treap) {
if !tsTree.less(tsTree.max(), tgTree.min()) {
func (tsTree *Treap) JoinExclusive(tgTree *Treap) {

if tsTree.Size() != 0 && tgTree.Size() != 0 && !tsTree.less(tsTree.Max(), tgTree.Min()) {
panic("Trees are not range-disjoint")
}

*tsTree.rootPtr = __joinExclusive(tsTree.rootPtr, tgTree.rootPtr)
*tgTree.rootPtr = nullNodePtr
}

// Return the key located in the position pos respect to the order of the keys.
// The item is retrieved in O(log n) expected time.
// Panic if pos is greater or equal to the number of elements stored into the tree
func (tree *Treap) choose(pos int) interface{} {
func (tree *Treap) Choose(pos int) interface{} {

root := *tree.rootPtr
if pos >= root.count {
Expand Down Expand Up @@ -461,14 +463,14 @@ func __rank(root *Node, key interface{}, less func(i1, i2 interface{}) bool) int
// order of all keys stored in the tree. Otherwise, the method returns (false, Undetermined)
// for indicating that the key is not in the tree.
// The computation spends O(log n) expected time
func (tree *Treap) rank(key interface{}) (ok bool, pos int) {
func (tree *Treap) RankInOrder(key interface{}) (ok bool, pos int) {

pos = __rank(*tree.rootPtr, key, tree.less)
ok = pos != notFound
return
}

// Helper that split tree root by position i. i - 1 first minor keys are returned in l,
// Helper that SplitByKey tree root by position i. i - 1 first minor keys are returned in l,
// while keys the following in r
func __splitPos(root *Node, i int) (l, r *Node) {

Expand Down Expand Up @@ -496,8 +498,8 @@ func __splitPos(root *Node, i int) (l, r *Node) {
return
}

// split tree in ts = [min, i) and tg = [i, max). After operation tree becomes empty
func (tree *Treap) splitPos(i int) (ts, tg *Treap) {
// SplitByKey tree in ts = [Min, i) and tg = [i, Max). After operation tree becomes empty
func (tree *Treap) SplitByPosition(i int) (ts, tg *Treap) {

root := *tree.rootPtr
if i > root.count {
Expand All @@ -521,19 +523,19 @@ func (tree *Treap) splitPos(i int) (ts, tg *Treap) {
}

// Extract from tree all the keys in [beginPos, endPos). tree looses the extracted range
func (tree *Treap) extractRange(beginPos, endPos int) *Treap {
func (tree *Treap) ExtractRange(beginPos, endPos int) *Treap {

if beginPos > endPos || endPos > (*tree.rootPtr).count-1 {
panic(fmt.Sprintf("Invalid positions %d %d respect to number of keys %d",
beginPos, endPos, (*tree.rootPtr).count))
}

treeAux, endTree := tree.splitPos(endPos)
beginTree, result := treeAux.splitPos(beginPos)
treeAux, endTree := tree.SplitByPosition(endPos)
beginTree, result := treeAux.SplitByPosition(beginPos)

beginTree.joinExclusive(endTree)
beginTree.JoinExclusive(endTree)

tree.swap(beginTree)
tree.Swap(beginTree)

return result
}
Expand Down Expand Up @@ -600,29 +602,29 @@ func NewIterator(tree *Treap) *Iterator {
return it
}

func (it *Iterator) resetFirst() {
func (it *Iterator) ResetFirst() {
emptyStack(it)
initialize(it)
}

func (it *Iterator) resetLast() {
func (it *Iterator) ResetLast() {
emptyStack(it)
advanceToMax(it, it.root)
}

func (it *Iterator) hasCurr() bool {
func (it *Iterator) HasCurr() bool {
return it.curr != nullNodePtr
}

func (it *Iterator) getCurr() interface{} {
if !it.hasCurr() {
func (it *Iterator) GetCurr() interface{} {
if !it.HasCurr() {
panic("Iterator has not current item")
}
return it.curr.key
}

func (it *Iterator) next() {
if !it.hasCurr() {
func (it *Iterator) Next() {
if !it.HasCurr() {
panic("Iterator has not current item")
}
it.curr = it.curr.rlink
Expand All @@ -638,6 +640,8 @@ func (it *Iterator) next() {
}
}

// TODO Implement Prev method

// Simple BST checker; Not completely correct
func checkBST(node *Node, less func(i1, i2 interface{}) bool) bool {

Expand Down
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