- Add Left(), Right(), Floor() and Ceiling() function to the red black tree with test and documentation update

README.md

@@ -471,6 +471,12 @@ func main() {
 	tree.Clear() // empty
 	tree.Empty() // true
 	tree.Size()  // 0
+
+    // Other:
+    tree.Left() // gets the left-most (min) node
+    tree.Right() // get the right-most (max) node
+    tree.Floor(1) // get the floor node
+    tree.Ceiling(1) // get the ceiling node
 }
 ```
 

examples/redblacktreeextended.go

@@ -95,64 +95,6 @@ func (tree *RedBlackTreeExtended) getMaxFromNode(node *rbt.Node) (foundNode *rbt
 	}
 }
 
-// Find ceiling node of the input key, return the ceiling node or nil if no ceiling is found.
-// Second return parameter is true if ceiling was found, otherwise false.
-//
-// Ceiling node is defined as the smallest node that is larger than or equal to the given node.
-// A ceiling node may not be found, either because the tree is empty, or because
-// all nodes in the tree is smaller than the given node.
-//
-// Key should adhere to the comparator's type assertion, otherwise method panics.
-func (tree *RedBlackTreeExtended) Ceiling(key interface{}) (ceiling *rbt.Node, found bool) {
-	found = false
-	node := tree.Root
-	for node != nil {
-		compare := tree.Comparator(key, node.Key)
-		switch {
-		case compare == 0:
-			return node, true
-		case compare < 0:
-			ceiling, found = node, true
-			node = node.Left
-		case compare > 0:
-			node = node.Right
-		}
-	}
-	if found {
-		return ceiling, true
-	}
-	return nil, false
-}
-
-// Find floor node of the input key, return the floor node or nil if no ceiling is found.
-// Second return parameter is true if floor was found, otherwise false.
-//
-// Floor node is defined as the largest node that is smaller than or equal to the given node.
-// A floor node may not be found, either because the tree is empty, or because
-// all nodes in the tree is larger than the given node.
-//
-// Key should adhere to the comparator's type assertion, otherwise method panics.
-func (tree *RedBlackTreeExtended) Floor(key interface{}) (floor *rbt.Node, found bool) {
-	found = false
-	node := tree.Root
-	for node != nil {
-		compare := tree.Comparator(key, node.Key)
-		switch {
-		case compare == 0:
-			return node, true
-		case compare < 0:
-			node = node.Left
-		case compare > 0:
-			floor, found = node, true
-			node = node.Right
-		}
-	}
-	if found {
-		return floor, true
-	}
-	return nil, false
-}
-
 func print(tree *RedBlackTreeExtended) {
 	max, _ := tree.GetMax()
 	min, _ := tree.GetMin()
@@ -190,30 +132,4 @@ func RedBlackTreeExtendedExample() {
 	// Value for min key: c
 	// RedBlackTree
 	// └── 3
-
-	// Ceiling and Floor functions
-	tree = RedBlackTreeExtended{rbt.NewWithIntComparator()}
-	tree.Put(1, "a")
-	tree.Put(2, "b")
-	tree.Put(4, "d")
-	tree.Put(6, "f")
-	tree.Put(7, "g")
-
-	//index, ceiling, floor
-	testValues := [][]interface{}{
-		{0, 1, nil},
-		{1, 1, 1},
-		{2, 2, 2},
-		{3, 4, 2},
-		{4, 4, 4},
-		{5, 6, 4},
-		{6, 6, 6},
-		{7, 7, 7},
-		{8, nil, 7},
-	}
-	for _, tt := range testValues {
-		actualCeiling, _ := tree.Ceiling(tt[0])
-		actualFloor, _ := tree.Floor(tt[0])
-		fmt.Printf("test key %d, expected (%d, %d), actual (%d, %d)\n", tt[0], tt[1], tt[2], actualCeiling.Key, actualFloor.Key)
-	}
 }

trees/redblacktree/redblacktree.go

@@ -186,22 +186,84 @@ func (tree *Tree) Values() []interface{} {
 	return values
 }
 
-// Returns the left-most key.
-func (tree *Tree) Left() interface{} {
-	left := tree.leftNode()
-	if left == nil {
-		return nil
+// Returns the left-most (min) node or nil if tree is empty.
+func (tree *Tree) Left() *Node {
+	var parent *Node
+	current := tree.Root
+	for current != nil {
+		parent = current
+		current = current.Left
 	}
-	return left.Key
+	return parent
 }
 
-// Returns the right-most key.
-func (tree *Tree) Right() interface{} {
-	right := tree.rightNode()
-	if right == nil {
-		return nil
+// Returns the right-most (max) node or nil if tree is empty.
+func (tree *Tree) Right() *Node {
+	var parent *Node
+	current := tree.Root
+	for current != nil {
+		parent = current
+		current = current.Right
+	}
+	return parent
+}
+
+// Find floor node of the input key, return the floor node or nil if no ceiling is found.
+// Second return parameter is true if floor was found, otherwise false.
+//
+// Floor node is defined as the largest node that is smaller than or equal to the given node.
+// A floor node may not be found, either because the tree is empty, or because
+// all nodes in the tree is larger than the given node.
+//
+// Key should adhere to the comparator's type assertion, otherwise method panics.
+func (tree *Tree) Floor(key interface{}) (floor *Node, found bool) {
+	found = false
+	node := tree.Root
+	for node != nil {
+		compare := tree.Comparator(key, node.Key)
+		switch {
+		case compare == 0:
+			return node, true
+		case compare < 0:
+			node = node.Left
+		case compare > 0:
+			floor, found = node, true
+			node = node.Right
+		}
+	}
+	if found {
+		return floor, true
+	}
+	return nil, false
+}
+
+// Find ceiling node of the input key, return the ceiling node or nil if no ceiling is found.
+// Second return parameter is true if ceiling was found, otherwise false.
+//
+// Ceiling node is defined as the smallest node that is larger than or equal to the given node.
+// A ceiling node may not be found, either because the tree is empty, or because
+// all nodes in the tree is smaller than the given node.
+//
+// Key should adhere to the comparator's type assertion, otherwise method panics.
+func (tree *Tree) Ceiling(key interface{}) (ceiling *Node, found bool) {
+	found = false
+	node := tree.Root
+	for node != nil {
+		compare := tree.Comparator(key, node.Key)
+		switch {
+		case compare == 0:
+			return node, true
+		case compare < 0:
+			ceiling, found = node, true
+			node = node.Left
+		case compare > 0:
+			node = node.Right
+		}
 	}
-	return right.Key
+	if found {
+		return ceiling, true
+	}
+	return nil, false
 }
 
 // Removes all nodes from the tree.
@@ -250,26 +312,6 @@ func (tree *Tree) inOrder() []*Node {
 	return nodes
 }
 
-func (tree *Tree) leftNode() *Node {
-	var parent *Node
-	current := tree.Root
-	for current != nil {
-		parent = current
-		current = current.Left
-	}
-	return parent
-}
-
-func (tree *Tree) rightNode() *Node {
-	var parent *Node
-	current := tree.Root
-	for current != nil {
-		parent = current
-		current = current.Right
-	}
-	return parent
-}
-
 func output(node *Node, prefix string, isTail bool, str *string) {
 	if node.Right != nil {
 		newPrefix := prefix

trees/redblacktree/redblacktree_test.go

@@ -60,6 +60,38 @@ func TestRedBlackTree(t *testing.T) {
 		t.Errorf("Got %v expected %v", actualValue, expectedValue)
 	}
 
+	// test Left()
+	if actualValue, expectedValue := fmt.Sprintf("%d", tree.Left().Key), "1"; actualValue != expectedValue {
+		t.Errorf("Got %v expected %v", actualValue, expectedValue)
+	}
+	if actualValue, expectedValue := fmt.Sprintf("%s", tree.Left().Value), "a"; actualValue != expectedValue {
+		t.Errorf("Got %v expected %v", actualValue, expectedValue)
+	}
+
+	// test Right()
+	if actualValue, expectedValue := fmt.Sprintf("%d", tree.Right().Key), "7"; actualValue != expectedValue {
+		t.Errorf("Got %v expected %v", actualValue, expectedValue)
+	}
+	if actualValue, expectedValue := fmt.Sprintf("%s", tree.Right().Value), "g"; actualValue != expectedValue {
+		t.Errorf("Got %v expected %v", actualValue, expectedValue)
+	}
+
+	// test Floor()
+	if node, found := tree.Floor(4); node.Key != 4 || !found {
+		t.Errorf("Got %v expected %v", node.Key, 4)
+	}
+	if node, found := tree.Floor(0); node != nil || found {
+		t.Errorf("Got %v expected %v", node, "<nil>")
+	}
+
+	// test Ceiling()
+	if node, found := tree.Ceiling(4); node.Key != 4 || !found {
+		t.Errorf("Got %v expected %v", node.Key, 4)
+	}
+	if node, found := tree.Ceiling(8); node != nil || found {
+		t.Errorf("Got %v expected %v", node, "<nil>")
+	}
+
 	// key,expectedValue,expectedFound
 	tests1 := [][]interface{}{
 		{1, "a", true},
@@ -97,6 +129,11 @@ func TestRedBlackTree(t *testing.T) {
 		t.Errorf("Got %v expected %v", actualValue, expectedValue)
 	}
 
+	// test Values()
+	if actualValue, expectedValue := fmt.Sprintf("%s%s%s%s", tree.Values()...), "abcd"; actualValue != expectedValue {
+		t.Errorf("Got %v expected %v", actualValue, expectedValue)
+	}
+
 	// Test Size()
 	if actualValue := tree.Size(); actualValue != 4 {
 		t.Errorf("Got %v expected %v", actualValue, 7)
@@ -158,6 +195,25 @@ func TestRedBlackTree(t *testing.T) {
 		t.Errorf("Got %v expected %v", actualValue, true)
 	}
 
+	// test Left()
+	if actualValue, expectedValue := fmt.Sprintf("%s", tree.Left()), "<nil>"; actualValue != expectedValue {
+		t.Errorf("Got %s expected %s", actualValue, expectedValue)
+	}
+
+	// test Right()
+	if actualValue, expectedValue := fmt.Sprintf("%s", tree.Right()), "<nil>"; actualValue != expectedValue {
+		t.Errorf("Got %s expected %s", actualValue, expectedValue)
+	}
+
+	// test Floor()
+	if node, found := tree.Floor(1); node != nil || found {
+		t.Errorf("Got %v expected %v", node, "<nil>")
+	}
+
+	// test Ceiling()
+	if node, found := tree.Ceiling(1); node != nil || found {
+		t.Errorf("Got %v expected %v", node, "<nil>")
+	}
 }
 
 func BenchmarkRedBlackTree(b *testing.B) {