python: add problem 92 and unittest

Author: supercoderhawk

Python/sln_1_100/solution_91_100.py

@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 from typing import List
+from common_utils import ListNode
 
 
 class Solution_91_100(object):
@@ -23,6 +24,49 @@ def numDecodings(self, s: str) -> int:
                 prefix2num[candidate] = count
         return prefix2num[s]
 
+    def reverseBetween(self, head: ListNode, m: int, n: int) -> ListNode:
+        """
+        92
+        :param head:
+        :param m:
+        :param n:
+        :return:
+        """
+        if m == n:
+            return head
+        infix_tail = None
+        infix_head = None
+        node = None
+        idx = 1
+        while idx < m:
+            if node is None:
+                node = head
+            else:
+                node = node.next
+            idx += 1
+        prefix_tail = node
+
+        while idx <= n:
+            if node is None:
+                node = head
+            else:
+                node = node.next
+            infix_node = ListNode(node.val)
+            if infix_head is None:
+                infix_head = infix_tail = infix_node
+            else:
+                infix_node.next = infix_head
+                infix_head = infix_node
+
+            idx += 1
+        if prefix_tail is None:
+            new_head = infix_head
+        else:
+            new_head = head
+            prefix_tail.next = infix_head
+        infix_tail.next = node.next
+        return new_head
+
     def restoreIpAddresses(self, s: str) -> List[str]:
         """
         93

Python/sln_1_100/test_solution_91_100.py

@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 from unittest import TestCase
+from common_utils import *
 from sln_1_100.solution_91_100 import Solution_91_100
 
 
@@ -15,6 +16,16 @@ def test_numDecodings(self):
         self.assertEqual(self.sln.numDecodings("12"), 2)
         self.assertEqual(self.sln.numDecodings("226"), 3)
 
+    def test_reverseBetween(self):
+        ret = self.sln.reverseBetween(build_linked_list([1, 2, 3, 4, 5]), 2, 4)
+        assert print_linked_list(ret) == '1->4->3->2->5'
+
+        ret = self.sln.reverseBetween(build_linked_list([1, 2, 3, 4, 5]), 1, 4)
+        assert print_linked_list(ret) == '4->3->2->1->5'
+
+        ret = self.sln.reverseBetween(build_linked_list([1, 2, 3, 4, 5]), 2, 5)
+        print_linked_list(ret)
+
     def test_restoreIpAddresses(self):
         ret = self.sln.restoreIpAddresses("25525511135")
         self.assertEqual(ret, ['255.255.11.135', '255.255.111.35'])