Merge pull request #13 from fabiothiroki/linkedlist

add linked list problem

Author: fabiothiroki

linkedlist/removeduplicates/removeduplicates.go

@@ -0,0 +1,63 @@
+package removeduplicates
+
+import "fmt"
+
+// Node is a linked list representation
+type Node struct {
+	value int
+	next  *Node
+}
+
+// CountElements returns a map with each element occurrence
+func CountElements(head *Node) map[int]int {
+	m := make(map[int]int)
+
+	l := head
+	for l != nil {
+		m[head.value]++
+
+		l = l.next
+	}
+
+	return m
+}
+
+func RemoveElement(head *Node, element int) *Node {
+	if head.value == element {
+		return head.next
+	}
+
+	l := head
+	for l != nil {
+
+		if l.next != nil && l.next.value == element {
+			l.next = l.next.next
+		} else {
+			l = l.next
+		}
+	}
+	return head
+}
+
+// RemoveDuplicates returns a linked list without duplicated values
+func RemoveDuplicates(head *Node) *Node {
+	if head == nil {
+		return head
+	}
+
+	m := CountElements(head)
+
+	l2 := head
+	for l2 != nil {
+		if m[l2.value] > 1 {
+			head = RemoveElement(head, l2.value)
+			m[l2.value]--
+		}
+
+		l2 = l2.next
+	}
+
+	fmt.Println(head)
+
+	return head
+}

linkedlist/removeduplicates/removeduplicates_test.go

@@ -0,0 +1,29 @@
+package removeduplicates
+
+import "testing"
+
+func TestNilList(t *testing.T) {
+	r := RemoveDuplicates(nil)
+	if r != nil {
+		t.Errorf("Got: %p, want: nil.", r)
+	}
+}
+
+func TestDuplicatesList(t *testing.T) {
+	n2 := &Node{
+		value: 2,
+		next:  nil,
+	}
+
+	n1 := &Node{
+		value: 2,
+		next:  n2,
+	}
+
+	r := RemoveDuplicates(n1)
+
+	m := CountElements(r)
+	if m[2] != 1 {
+		t.Errorf("Got: %d, want: 1.", m[2])
+	}
+}