Hash table Resize

data-structures/hash-tables/ht.go

@@ -5,7 +5,7 @@ package ht
 
 import (
 	"errors"
-	"github.com/arnauddri/algorithms/data-structures/linked-list"
+	list "github.com/arnauddri/algorithms/data-structures/linked-list"
 	"math"
 )
 
@@ -115,3 +115,17 @@ func hashCode(s string) int {
 	}
 	return int(math.Abs(float64(hash)))
 }
+
+// Resizes table to desired capacity. ( if Possible )
+func (ht *HashTable) Resize(newCap int) error {
+	size := ht.Size
+	if ht.Capacity == newCap {
+		return errors.New("current capacity is as same the input number")
+	}
+	if newCap >= size {
+		ht.Capacity = newCap
+	} else {
+		return errors.New("there is not enough capacity to hold items. please enter a larger number")
+	}
+	return nil
+}

data-structures/hash-tables/ht_test.go

@@ -55,3 +55,32 @@ func TestHash(t *testing.T) {
 		t.Error()
 	}
 }
+
+func TestHashTable_Resize(t *testing.T) {
+	ht := New(1000)
+	ht.Put("foo", "bar")
+	ht.Put("fiz", "buzz")
+	ht.Put("bruce", "wayne")
+	ht.Put("peter", "parker")
+	ht.Put("clark", "kent")
+
+	actual := ht.Resize(10)
+
+	if actual != nil {
+		t.Errorf("resul = %v, want nil", actual)
+	}
+
+	actual = ht.Resize(10)
+	expected := "current capacity is as same the input number"
+
+	if actual.Error() != expected {
+		t.Errorf("resul = %v, want %v", actual, expected)
+	}
+
+	actual = ht.Resize(4)
+	expected = "there is not enough capacity to hold items. please enter a larger number"
+
+	if actual.Error() != expected {
+		t.Errorf("resul = %v, want %v", actual, expected)
+	}
+}