328 solved. (#60)

Author: zwfang

README.md

@@ -70,6 +70,7 @@ continually updating 😃.
 * [203. Remove Linked List Elements](src/0203_remove_linked_list_elements/remove_linked_list_elements.go)
 * [206. Reverse Linked List](src/0206_reverse_linked_list/reverse_linked_list.go)
 * [237. Delete Node in a Linked List](src/0237_delete_node_in_a_linked_list/dniall.go)
+* [328. Odd Even Linked List](src/0328_odd_even_linked_list/odd_even_linked_list.go)
 
 ### Dynamic Programming
 * [62. Unique Paths](./src/0062_unique_paths/unique_paths.go)   *`array`*

src/0328_odd_even_linked_list/odd_even_linked_list.go

@@ -0,0 +1,44 @@
+/*
+328. Odd Even Linked List
+https://leetcode.com/problems/odd-even-linked-list/
+
+Given a singly linked list, group all odd nodes together followed by the even nodes.
+Please note here we are talking about the node number and not the value in the nodes.
+
+You should try to do it in place.
+The program should run in O(1) space complexity and O(nodes) time complexity.
+
+Note:
+The relative order inside both the even and odd groups should remain as it was in the input.
+The first node is considered odd, the second node even and so on ...
+*/
+// time: 2019-01-07
+
+package oddevenlinkedlist
+
+// ListNode Definition for singly-linked list.
+type ListNode struct {
+	Val  int
+	Next *ListNode
+}
+
+// time complexity: O(n)
+// space complexity: O(1)
+func oddEvenList(head *ListNode) *ListNode {
+	if head == nil {
+		return head
+	}
+	var (
+		odd      = head
+		evenHead = head.Next
+		even     = evenHead
+	)
+	for even != nil && even.Next != nil {
+		odd.Next = even.Next
+		odd = odd.Next
+		even.Next = odd.Next
+		even = even.Next
+	}
+	odd.Next = evenHead
+	return head
+}

src/0328_odd_even_linked_list/odd_even_linked_list_test.go

@@ -0,0 +1,34 @@
+package oddevenlinkedlist
+
+import (
+	"reflect"
+	"testing"
+)
+
+func createSinglyLinkedList(nums []int) *ListNode {
+	head := &ListNode{}
+	cur := head
+
+	for _, num := range nums {
+		cur.Next = &ListNode{Val: num}
+		cur = cur.Next
+	}
+	return head.Next
+}
+
+func TestOddEvenList(t *testing.T) {
+	testCases := []*ListNode{
+		createSinglyLinkedList([]int{2, 1, 3, 5, 6, 4, 7}),
+		nil,
+	}
+	expected := []*ListNode{
+		createSinglyLinkedList([]int{2, 3, 6, 7, 1, 5, 4}),
+		nil,
+	}
+
+	for index, head := range testCases {
+		if res := oddEvenList(head); !reflect.DeepEqual(res, expected[index]) {
+			t.Errorf("expected %v, got %v", expected[index], res)
+		}
+	}
+}

src/README.md

@@ -78,6 +78,7 @@
 |0283|[Move Zeroes(solution1)](./0283_move_zeroes/move_zeroes.go) <br/>  [Move Zeroes(solution2)](./0283_move_zeroes/move_zeroes2.go)|Easy|*`array`*|
 |0300|[Longest Increasing Subsequence](./0300_longest_increasing_subsequence/lis.go)|Medium|*`dp`*|
 |0303|[303. Range Sum Query - Immutable](0303_range_sum_query/rsqim.go)|Easy||
+|0328|[328. Odd Even Linked List](0328_odd_even_linked_list/odd_even_linked_list.go)|Medium|*`singly linked list`*|
 |0343|[Integer Break](./0343_integer_break/integer_break.go)|Medium|*`recursion;`* *`memory search;`* *`dynamic programming`*|
 |0344|[344. Reverse String](0344_reverse_string/reverse_string.go)|Easy|*`double index`*|
 |0345|[345. Reverse Vowels of a String](0345_reverse_vowels_of_a_string/reverse_vowels.go)|Easy|*`double index`*|