Fixed insert and implemented push front

naren-m · Sep 19, 2021 · 743def3 · 743def3
1 parent 4253864
commit 743def3
Show file tree

Hide file tree

Showing 2 changed files with 27 additions and 12 deletions.
diff --git a/data_structures/linked_list.py b/data_structures/linked_list.py
@@ -56,9 +56,14 @@ def append(self, data):
         h.next = n
 
     def insert(self, index, value):
+        if index == 0:
+            self.pushFront(value)
+            return
+
         self._size += 1
         n = Node(value)
         h = self._moveTo(index -1)
+
         n.next = h.next
         h.next = n
 
@@ -96,7 +101,6 @@ def remove(self, value):
         prev.next = h.next
         self._size -= 1
 
-
     def deleteAtEnd(self):
         h = self.head
 
@@ -116,7 +120,7 @@ def deleteAtEnd(self):
     def pop(self, index=None):
 
         if index > self.size:
-            return
+            raise IndexError
 
         if index is None:
             self.deleteAtEnd()
@@ -142,8 +146,12 @@ def peekBack(self):
 
         return h.data
 
-    def pushFront(self):
-        pass
+    def pushFront(self, value):
+        self._size += 1
+        n = Node(value)
+        n.next = self.head
+        self.head = n
+        return
 
     def pushBack(self):
         pass

diff --git a/tests/test_linked_lists.py b/tests/test_linked_lists.py
@@ -25,13 +25,22 @@ def test_insert(self):
         for i in range(0, 10):
             ll.append(i)
 
-        ll.insert(value=10, index=9)
-
         expected = list(range(0, 10))
-        expected.insert(9, 10)
-        self.assertEqual(ll[9], 10)
 
-        self._checkEqual(ll, expected)
+        def _insert(index, val):
+            ll.insert(index, val)
+            expected.insert(index, val)
+            print(ll)
+            self.assertEqual(ll[index], val)
+            self._checkEqual(ll, expected)
+
+        _insert(9, 10)
+        _insert(0, 100)
+        _insert(1, 200)
+        _insert(0, 101)
+        _insert(ll.size, 1000)
+        _insert(ll.size, 1001)
+
 
     def _checkEqual(self, ll, expected):
         print('Expected: {}, Got: {}'.format(expected, ll))
@@ -96,11 +105,9 @@ def _pop(i):
         # _pop(4)
         # _pop(3)
         _pop(0)
+        _pop(1)
 
         # ll.pop(1)
-        print('----->', expected.pop())
-        _pop(1)
-        self._checkEqual(ll, expected)
 
         # print(expected, ll)