diff --git a/tree/heap/heap.go b/tree/heap/heap.go
index 126fb08..e376c30 100644
--- a/tree/heap/heap.go
+++ b/tree/heap/heap.go
@@ -110,7 +110,6 @@ func (h *Heap) Pop() (interface{}, bool) {
 
 	downvalue := h.elements[h.size]
 	var cidx, c1, c2 int
-	var cvalue1, cvalue2 interface{}
 	// down
 	for {
 		cidx = curidx << 1
@@ -119,11 +118,7 @@ func (h *Heap) Pop() (interface{}, bool) {
 		c2 = cidx + 2
 
 		if c2 < h.size {
-
-			cvalue2 = h.elements[c2]
-			cvalue1 = h.elements[c1]
-
-			if h.Compare(cvalue1, cvalue2) >= 0 {
+			if h.Compare(h.elements[c1], h.elements[c2]) >= 0 {
 				cidx = c1
 			} else {
 				cidx = c2
diff --git a/tree/heap/heap_test.go b/tree/heap/heap_test.go
index b4c90f8..ab4251d 100644
--- a/tree/heap/heap_test.go
+++ b/tree/heap/heap_test.go
@@ -9,48 +9,52 @@ import (
 )
 
 func TestHeapGrowSlimming(t *testing.T) {
-	h := New(compare.Int)
-	var results []int
-	for i := 0; i < 100; i++ {
-		v := randomdata.Number(0, 100)
-		results = append(results, v)
-		h.Put(v)
-	}
-	sort.Slice(results, func(i, j int) bool {
-		if results[i] > results[j] {
-			return true
+
+	for ii := 0; ii < 1000; ii++ {
+
+		h := New(compare.Int)
+		var results []int
+		for i := 0; i < 100; i++ {
+			v := randomdata.Number(0, 100)
+			results = append(results, v)
+			h.Put(v)
 		}
-		return false
-	})
+		sort.Slice(results, func(i, j int) bool {
+			if results[i] > results[j] {
+				return true
+			}
+			return false
+		})
 
-	if h.Size() != 100 || h.Empty() {
-		t.Error("size != 100")
-	}
-
-	for i := 0; !h.Empty(); i++ {
-		v, _ := h.Pop()
-		if results[i] != v {
-			t.Error("heap is error")
+		if h.Size() != 100 || h.Empty() {
+			t.Error("size != 100")
 		}
-	}
 
-	if h.Size() != 0 {
-		t.Error("size != 0")
-	}
+		for i := 0; !h.Empty(); i++ {
+			v, _ := h.Pop()
+			if results[i] != v {
+				t.Error("heap is error")
+			}
+		}
 
-	h.Put(1)
-	h.Put(5)
-	h.Put(2)
+		if h.Size() != 0 {
+			t.Error("size != 0")
+		}
 
-	if h.Values()[0] != 5 {
-		t.Error("top is not equal to 5")
-	}
+		h.Put(1)
+		h.Put(5)
+		h.Put(2)
 
-	h.Clear()
-	h.Reborn()
+		if h.Values()[0] != 5 {
+			t.Error("top is not equal to 5")
+		}
 
-	if !h.Empty() {
-		t.Error("clear reborn is error")
+		h.Clear()
+		h.Reborn()
+
+		if !h.Empty() {
+			t.Error("clear reborn is error")
+		}
 	}
 
 }
@@ -104,6 +108,20 @@ func TestHeapPushTopPop(t *testing.T) {
 	}
 }
 
+// func BenchmarkPush(b *testing.B) {
+// 	h := New(compare.Int)
+// 	b.N = 40000000
+// 	var results []int
+// 	for i := 0; i < b.N; i++ {
+// 		results = append(results, randomdata.Number(0, 1000000000))
+// 	}
+
+// 	b.ResetTimer()
+// 	for _, v := range results {
+// 		h.Put(v)
+// 	}
+// }
+
 // func Int(k1, k2 interface{}) int {
 // 	c1 := k1.(int)
 // 	c2 := k2.(int)