solve problem Odd Even Linked List

Author: P-ppc

README.md

@@ -239,6 +239,7 @@ All solutions will be accepted!
 |208|[Implement Trie Prefix Tree](https://leetcode-cn.com/problems/implement-trie-prefix-tree/description/)|[java/py/js](./algorithms/ImplementTriePrefixTree)|Medium|
 |114|[Flatten Binary Tree To Linked List](https://leetcode-cn.com/problems/flatten-binary-tree-to-linked-list/description/)|[java/py/js](./algorithms/FlattenBinaryTreeToLinkedList)|Medium|
 |284|[Peeking Iterator](https://leetcode-cn.com/problems/peeking-iterator/description/)|[java/py](./algorithms/PeekingIterator)|Medium|
+|328|[Odd Even Linked List](https://leetcode-cn.com/problems/odd-even-linked-list/description/)|[java/py/js](./algorithms/OddEvenLinkedList)|Medium|
 
 # Database
 |#|Title|Solution|Difficulty|

algorithms/OddEvenLinkedList/README.md

@@ -0,0 +1,2 @@
+# Odd Even Linked List
+This problem is easy to solve

algorithms/OddEvenLinkedList/Solution.java

@@ -0,0 +1,39 @@
+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ *     int val;
+ *     ListNode next;
+ *     ListNode(int x) { val = x; }
+ * }
+ */
+class Solution {
+    public ListNode oddEvenList(ListNode head) {
+        if (head == null) return null;
+        
+        int length = 0;
+        ListNode tail = head,
+                 node = head;
+        
+        while (node != null) {
+            length++;
+            tail = node;
+            node = node.next;
+        }
+        
+        ListNode pre = head;
+        int i = 1;
+        node = pre.next;
+        
+        while (i < length && node.next != null) {
+            pre.next = node.next;
+            node.next = null;
+            tail.next = node;
+            tail = tail.next;
+            pre = pre.next;
+            node = pre.next;
+            i += 2;
+        }
+        
+        return head;
+    }
+}

algorithms/OddEvenLinkedList/solution.js

@@ -0,0 +1,40 @@
+/**
+ * Definition for singly-linked list.
+ * function ListNode(val) {
+ *     this.val = val;
+ *     this.next = null;
+ * }
+ */
+/**
+ * @param {ListNode} head
+ * @return {ListNode}
+ */
+var oddEvenList = function(head) {
+    if (!head) return null
+    
+    let length = 0,
+        tail = head,
+        node = head
+    
+    while (node) {
+        length++
+        tail = node
+        node = node.next
+    }
+    
+    let pre = head,
+        i = 1
+    node = pre.next
+
+    while (i < length && node.next) {
+        pre.next = node.next
+        node.next = null
+        tail.next = node
+        tail = tail.next
+        pre = pre.next
+        node = pre.next     
+        i += 2
+    }
+    
+    return head
+};

algorithms/OddEvenLinkedList/solution.py

@@ -0,0 +1,34 @@
+# Definition for singly-linked list.
+# class ListNode(object):
+#     def __init__(self, x):
+#         self.val = x
+#         self.next = None
+
+class Solution(object):
+    def oddEvenList(self, head):
+        """
+        :type head: ListNode
+        :rtype: ListNode
+        """
+        if not head:
+            return None
+        
+        length = 0
+        tail = node = head
+        while node:
+            length += 1
+            tail, node = node, node.next
+        
+        pre = head
+        node = pre.next
+        i = 1
+        while i < length and node.next:
+            pre.next = node.next
+            node.next = None
+            tail.next = node
+            tail = tail.next
+            pre = pre.next
+            node = pre.next
+            i += 2
+        return head
+