Merge pull request #1530 from ivanpenaloza/january28

adding algo

Author: ivanpenaloza

src/my_project/interviews/top_150_questions_round_22/ex_62_remove_duplicates_from_sorted_linked_list_ii.py

@@ -0,0 +1,32 @@
+from typing import List, Union, Collection, Mapping, Optional
+from abc import ABC, abstractmethod
+
+# Definition for singly-linked list.
+class ListNode:
+    def __init__(self, x):
+        self.val = x
+        self.next = None
+
+class Solution:
+    def deleteDuplicates(self, head: Optional[ListNode]) -> Optional[ListNode]:
+        # Create a dummy node to handle edge cases where head is removed
+        dummy = ListNode(0)
+        dummy.next = head
+        prev = dummy
+        
+        while head:
+            # Check if current node has duplicates
+            if head.next and head.val == head.next.val:
+                # Skip all nodes with the same value
+                while head.next and head.val == head.next.val:
+                    head = head.next
+                # Link prev to the node after duplicates
+                prev.next = head.next
+            else:
+                # No duplicate, move prev forward
+                prev = prev.next
+            
+            # Move to next node
+            head = head.next
+        
+        return dummy.next

src/my_project/interviews_typescript/top_150_questions_round_1/ex_62_remove_duplicates_from_sorted_linked_list_ii.ts

@@ -0,0 +1,28 @@
+import { ListNode } from './ListNode';   
+
+function deleteDuplicates(head: ListNode | null): ListNode | null {
+    // Create a dummy node to handle edge cases where head is removed
+    const dummy = new ListNode(0);
+    dummy.next = head;
+    let prev = dummy;
+    
+    while (head) {
+        // Check if current node has duplicates
+        if (head.next && head.val === head.next.val) {
+            // Skip all nodes with the same value
+            while (head.next && head.val === head.next.val) {
+                head = head.next;
+            }
+            // Link prev to the node after duplicates
+            prev.next = head.next;
+        } else {
+            // No duplicate, move prev forward
+            prev = prev.next!;
+        }
+        
+        // Move to next node
+        head = head.next;
+    }
+    
+    return dummy.next;
+}

tests/test_150_questions_round_22/test_62_remove_duplicates_from_sorted_linked_list_ii_round_22.py

@@ -0,0 +1,60 @@
+import unittest
+from src.my_project.interviews.top_150_questions_round_22\
+.ex_62_remove_duplicates_from_sorted_linked_list_ii import Solution, ListNode
+
+class RemoveDuplicatesFromSortedLinkedListsIITestCase(unittest.TestCase):
+
+    def create_linked_list(self, values):
+        """
+        Helper function to create a linked list from a list of values.
+        
+        :param values: List of node values
+        :return: Head of the linked list
+        """
+        if not values:
+            return None
+        
+        head = ListNode(values[0])
+        current = head
+        
+        for val in values[1:]:
+            current.next = ListNode(val)
+            current = current.next
+        
+        return head
+
+    def linked_list_to_list(self, head):
+        """
+        Helper function to convert linked list to Python list.
+        
+        :param head: Head of the linked list
+        :return: List of values
+        """
+        result = []
+        current = head
+        
+        while current:
+            result.append(current.val)
+            current = current.next
+        
+        return result
+
+    def test_first_pattern(self):
+        # Example 1: Input: head = [1,2,3,3,4,4,5]
+        # Output: [1,2,5]
+        solution = Solution()
+        head = self.create_linked_list([1, 2, 3, 3, 4, 4, 5])
+        output = solution.deleteDuplicates(head)
+        result = self.linked_list_to_list(output)
+        target = [1, 2, 5]
+        self.assertEqual(result, target)
+
+    def test_second_pattern(self):
+        # Example 2: Input: head = [1,1,1,2,3]
+        # Output: [2,3]
+        solution = Solution()
+        head = self.create_linked_list([1, 1, 1, 2, 3])
+        output = solution.deleteDuplicates(head)
+        result = self.linked_list_to_list(output)
+        target = [2, 3]
+        self.assertEqual(result, target)