Reversing linked list using iterative method

Author: keshavsingh3197

HackerRank/Data Structure/Linked Lists/Linked-Lists.ipynb

@@ -331,6 +331,105 @@
    "source": [
     "# Reverse a linked list"
    ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "n=b"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 35,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdin",
+     "output_type": "stream",
+     "text": [
+      " 4\n",
+      " 12\n",
+      " 434\n",
+      " 66\n",
+      " 22\n"
+     ]
+    },
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Linked Lists\n",
+      "12\n",
+      "434\n",
+      "66\n",
+      "22\n",
+      "Linked Lists After Reversing\n",
+      "22\n",
+      "66\n",
+      "434\n",
+      "12\n"
+     ]
+    }
+   ],
+   "source": [
+    "# %load Reverse-linked-list.py\n",
+    "class node:\n",
+    "    def __init__(self,data):\n",
+    "        self.data=data\n",
+    "        self.next=None\n",
+    "class LinkedList:\n",
+    "    def __init__(self):\n",
+    "        self.start=None\n",
+    "    def display(self):\n",
+    "        if self.start==None:\n",
+    "            print('list is empty')\n",
+    "        else:\n",
+    "            temp=self.start\n",
+    "            while temp:\n",
+    "                print(temp.data)\n",
+    "                temp=temp.next\n",
+    "    def reversing_linked_list(self):\n",
+    "        current=self.start\n",
+    "        previous=None\n",
+    "        while current:\n",
+    "            temp=current.next\n",
+    "            current.next=previous\n",
+    "            previous=current\n",
+    "            current=temp\n",
+    "        self.start=previous\n",
+    "                \n",
+    "l=LinkedList()\n",
+    "for _ in range(int(input())):\n",
+    "    n=int(input())\n",
+    "    if l .start==None:\n",
+    "        l.start=node(n)\n",
+    "        ptr=l.start\n",
+    "    else:\n",
+    "        ptr.next=node(n)\n",
+    "        ptr=ptr.next\n",
+    "print('Linked Lists')\n",
+    "l.display()\n",
+    "print('Linked Lists After Reversing')\n",
+    "l.reversing_linked_list()\n",
+    "l.display()"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Compare two linked lists"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": []
   }
  ],
  "metadata": {

…kerRank/Linked Lists/print-in-reverse.py …ture/Linked Lists/Reverse-linked-list.pyHackerRank/Linked Lists/print-in-reverse.py renamed to HackerRank/Data Structure/Linked Lists/Reverse-linked-list.py HackerRank/Linked Lists/print-in-reverse.py renamed to HackerRank/Data Structure/Linked Lists/Reverse-linked-list.py

@@ -13,17 +13,16 @@ def display(self):
             while temp:
                 print(temp.data)
                 temp=temp.next
-    def display_reverse(self,head):
-        if head:
-            self.display_reverse(head.next)
-            print(head.data)
-    def InsertAtHead(self,n):
-        if self.start is None:
-            self.start=node(n)
-        else:
-            temp=self.start
-            self.start=node(n)
-            self.start.next=temp
+    def reversing_linked_list(self):
+        current=self.start
+        previous=None
+        while current:
+            temp=current.next
+            current.next=previous
+            previous=current
+            current=temp
+        self.start=previous
+                
 l=LinkedList()
 for _ in range(int(input())):
     n=int(input())
@@ -33,4 +32,8 @@ def InsertAtHead(self,n):
     else:
         ptr.next=node(n)
         ptr=ptr.next
-l.display_reverse(l.start)
+print('Linked Lists')
+l.display()
+print('Linked Lists After Reversing')
+l.reversing_linked_list()
+l.display()