82. Remove Duplicates from Sorted List II

README.md

@@ -59,6 +59,7 @@ continually updating 😃.
 * [24. Swap Nodes in Pairs](src/0024_swap_nodes_in_pairs/swap_nodes_in_pairs.go)
 * [25. Reverse Nodes in k-Group](./src/0025_reverse_nodes_in_k_group/reverse_node_k_group.go)
 * [61. Rotate List](./src/0061_rotate_list/rotate_list.go)
+* [82. Remove Duplicates from Sorted List II](src/0082_remove_duplicates_from_sorted_list_2/rdfsl.go)
 
 ### Dynamic Programming
 * [62. Unique Paths](./src/0062_unique_paths/unique_paths.go)   *`array`*

src/0082_remove_duplicates_from_sorted_list_2/rdfsl.go

@@ -0,0 +1,40 @@
+/*
+82. Remove Duplicates from Sorted List II
+https://leetcode.com/problems/remove-duplicates-from-sorted-list-ii/
+
+Given a sorted linked list, delete all nodes that have duplicate numbers,
+leaving only distinct numbers from the original list.
+*/
+// time: 2019-01-04
+
+package rdfsl
+
+// ListNode Definition for singly-linked list.
+type ListNode struct {
+	Val  int
+	Next *ListNode
+}
+
+// time complexity: O(n)
+// space complexity: O(1)
+func deleteDuplicates(head *ListNode) *ListNode {
+	dummyHead := &ListNode{}
+	dummyHead.Next = head
+
+	pre := dummyHead
+	cur := head
+
+	for cur != nil && cur.Next != nil {
+		if cur.Val == cur.Next.Val {
+			num := cur.Val
+			for cur != nil && cur.Val == num {
+				cur = cur.Next
+			}
+			pre.Next = cur
+		} else {
+			pre = cur
+			cur = cur.Next
+		}
+	}
+	return dummyHead.Next
+}

src/0082_remove_duplicates_from_sorted_list_2/rdfsl_test.go

@@ -0,0 +1,34 @@
+package rdfsl
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestDeleteDuplicates(t *testing.T) {
+	testCases := []*ListNode{
+		createSingleLinkedList([]int{1, 2, 3, 3, 4, 4, 5}),
+		createSingleLinkedList([]int{1, 1, 1, 2, 3}),
+	}
+
+	expected := []*ListNode{
+		createSingleLinkedList([]int{1, 2, 5}),
+		createSingleLinkedList([]int{2, 3}),
+	}
+
+	for index, head := range testCases {
+		if res := deleteDuplicates(head); !reflect.DeepEqual(res, expected[index]) {
+			t.Errorf("expected %v, got %v", expected[index], res)
+		}
+	}
+}
+
+func createSingleLinkedList(nums []int) *ListNode {
+	head := &ListNode{}
+	cur := head
+	for _, num := range nums {
+		cur.Next = &ListNode{Val: num}
+		cur = cur.Next
+	}
+	return head.Next
+}

src/README.md

@@ -40,6 +40,7 @@
 |0077|[77. Combinations](0077_combinations/combinations.go)|Medium|*`backtracking;`**`combine`*|
 |0079|[79. Word Search](0079_word_search/word_search.go)|Medium|*`backtracking;`**`array`*|
 |0080|[80. Remove Duplicates from Sorted Array II](0080_remove_duplicates_from_sorted_array2/rdfsa2.go)|Medium|*`double index`*|
+|0082|[82. Remove Duplicates from Sorted List II](0082_remove_duplicates_from_sorted_list_2/rdfsl.go)|Medium|*`linked list`*|
 |0088|[88. Merge Sorted Array](0088_merge_sorted_array/msa.go)|Easy|*`sort`*|
 |0094|[Binary Tree Inorder Traversal](./0094_binary_tree_inorder_traversal/binary_tree_inorder_traversal.go)|Medium|*`binary tree`*|
 |0100|[Same Tree](./0100_same_tree/same_tree.go)|Easy|*`binary tree`*|