solve problem Reverse Linked List

Author: P-ppc

README.md

@@ -103,6 +103,7 @@ All solutions will be accepted!
 |492|[Construct The Rectangle](https://leetcode-cn.com/problems/construct-the-rectangle/description/)|[java/py/js]|(./algorithms/ConstructTheRectangle)|Easy|
 |447|[Number Of Boomerangs](https://leetcode-cn.com/problems/number-of-boomerangs/description/)|[java/py/js](./algorithms/NumberOfBoomerangs)|Easy|
 |824|[Goat Latin](https://leetcode-cn.com/problems/goat-latin/description/)|[java/py/js](./algorithms/GoatLatin)|Easy|
+|206|[Reverse Linked List](https://leetcode-cn.com/problems/reverse-linked-list/description/)|[java/py/js](./algorithms/ReverseLinkedList)|Easy|
 
 # Database
 |#|Title|Solution|Difficulty|

algorithms/ReverseLinkedList/README.md

@@ -0,0 +1,23 @@
+# Reverse Linked List
+This problem is easy to solve, the loop solution is like below:
+```
+# Definition for singly-linked list.
+# class ListNode(object):
+#     def __init__(self, x):
+#         self.val = x
+#         self.next = None
+
+class Solution(object):
+    def reverseList(self, head):
+        """
+        :type head: ListNode
+        :rtype: ListNode
+        """
+        node = None
+        while head:
+            temp = ListNode(head.val)
+            temp.next = node
+            node = temp
+            head = head.next
+        return node
+```

algorithms/ReverseLinkedList/Solution.java

@@ -0,0 +1,25 @@
+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ *     int val;
+ *     ListNode next;
+ *     ListNode(int x) { val = x; }
+ * }
+ */
+class Solution {
+    public ListNode reverseList(ListNode head) {
+        return reverseListRecursively(null, head);
+    }
+    
+    public ListNode reverseListRecursively(ListNode pre, ListNode cur) {
+        if (cur == null) return null;
+        if (cur.next == null) {
+            cur.next = pre;
+            return cur;
+        }
+        
+        ListNode next = cur.next;
+        cur.next = pre;
+        return reverseListRecursively(cur, next);
+    }
+}

algorithms/ReverseLinkedList/solution.js

@@ -0,0 +1,26 @@
+/**
+ * Definition for singly-linked list.
+ * function ListNode(val) {
+ *     this.val = val;
+ *     this.next = null;
+ * }
+ */
+/**
+ * @param {ListNode} head
+ * @return {ListNode}
+ */
+var reverseList = function(head) {
+    return reverseListRecursively(null, head)
+};
+
+var reverseListRecursively = function (pre, cur) {
+    if (cur === null) return null
+    if (cur.next === null) {
+        cur.next = pre
+        return cur
+    }
+    
+    next = cur.next
+    cur.next = pre
+    return reverseListRecursively(cur, next)
+}

algorithms/ReverseLinkedList/solution.py

@@ -0,0 +1,24 @@
+# Definition for singly-linked list.
+# class ListNode(object):
+#     def __init__(self, x):
+#         self.val = x
+#         self.next = None
+
+class Solution(object):
+    def reverseList(self, head):
+        """
+        :type head: ListNode
+        :rtype: ListNode
+        """
+        return self.reverseListRecursively(None, head)
+    
+    def reverseListRecursively(self, pre, cur):
+        if cur == None:
+            return None
+        if cur.next == None:
+            cur.next = pre
+            return cur
+        nxt = cur.next
+        cur.next = pre
+        return self.reverseListRecursively(cur, nxt)
+