Fix: pairing heap don't work then using Delete not DelateMin to delet…

pairing/pairing_heap.go

@@ -6,8 +6,9 @@
 package pairing
 
 import (
-	heap "github.com/theodesp/go-heaps"
 	"fmt"
+
+	heap "github.com/theodesp/go-heaps"
 )
 
 // PairHeap implements the Extended interface
@@ -16,7 +17,7 @@ var _ heap.Extended = (*PairHeap)(nil)
 // PairHeap is an implementation of a Pairing Heap.
 // The zero value for PairHeap Root is an empty Heap.
 type PairHeap struct {
-	root       *node
+	root *node
 }
 
 // node contains the current item and the list if the sub-heaps
@@ -126,12 +127,11 @@ func (p *PairHeap) Insert(item heap.Item) heap.Item {
 	return item
 }
 
-
 // toDelete details what item to remove in a node call.
 type toDelete int
 
 const (
-	removeItem toDelete = iota   // removes the given item
+	removeItem toDelete = iota // removes the given item
 	removeMin                  // removes min item in the heap
 )
 
@@ -162,6 +162,9 @@ func (p *PairHeap) deleteItem(item heap.Item, typ toDelete) heap.Item {
 			node := p.root.findNode(item)
 			if node == nil {
 				return nil
+			} else if node == p.root {
+				result = *p.root
+				p.root = mergePairs(p.root, p.root.children)
 			} else {
 				children := node.detach()
 				p.root.children = append(p.root.children, children...)
@@ -212,7 +215,6 @@ func (p *PairHeap) Find(item heap.Item) heap.Item {
 	return found
 }
 
-
 // Do calls function cb on each element of the PairingHeap, in order of appearance.
 // The behavior of Do is undefined if cb changes *p.
 func (p *PairHeap) Do(it heap.ItemIterator) {

pairing/pairing_heap_test.go

@@ -1,13 +1,14 @@
 package pairing
 
 import (
-	"testing"
-	"github.com/stretchr/testify/suite"
-	"github.com/stretchr/testify/assert"
-	heap "github.com/theodesp/go-heaps"
 	"fmt"
 	"math/rand"
+	"testing"
 	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/suite"
+	heap "github.com/theodesp/go-heaps"
 )
 
 type PairingHeapTestSuite struct {
@@ -156,8 +157,8 @@ func (suite *PairingHeapTestSuite) TestFind() {
 	suite.heap.Insert(Int(4))
 
 	item = suite.heap.Find(Int(4))
-	assert.NotNil(suite.T(),item)
-	assert.Equal(suite.T(),item, Int(4))
+	assert.NotNil(suite.T(), item)
+	assert.Equal(suite.T(), item, Int(4))
 
 	suite.heap.Insert(Int(8))
 	suite.heap.Insert(Int(2))
@@ -166,8 +167,8 @@ func (suite *PairingHeapTestSuite) TestFind() {
 	suite.heap.Insert(Int(9))
 
 	item = suite.heap.Find(Int(9))
-	assert.NotNil(suite.T(),item)
-	assert.Equal(suite.T(),item, Int(9))
+	assert.NotNil(suite.T(), item)
+	assert.Equal(suite.T(), item, Int(9))
 	testMinHeapInvariance(suite)
 }
 
@@ -181,6 +182,20 @@ func (suite *PairingHeapTestSuite) TestAdjust() {
 	testMinHeapInvariance(suite)
 }
 
+func (suite *PairingHeapTestSuite) TestDeleteBug() {
+	vs := []int{3, 4, 5, 6, 7, 8}
+	for _, v := range vs {
+		suite.heap.Insert(Int(v))
+	}
+	assert.Equal(suite.T(), Int(3), suite.heap.Delete(Int(3)))
+	assert.Nil(suite.T(), suite.heap.Find(Int(3)))
+	i := suite.heap.DeleteMin()
+	assert.Equal(suite.T(), Int(4), i)
+
+	assert.Equal(suite.T(), Int(6), suite.heap.Delete(Int(6)))
+	assert.Nil(suite.T(), suite.heap.Find(Int(6)))
+}
+
 func (suite *PairingHeapTestSuite) TestDelete() {
 	for _, v := range rang(10) {
 		suite.heap.Insert(v)
@@ -194,4 +209,4 @@ func (suite *PairingHeapTestSuite) TestDelete() {
 
 func Int(value int) heap.Integer {
 	return heap.Integer(value)
-}
+}