Merge pull request #10 from jreuben11/leetcode

refresher - single linked list

Author: jreuben11

leetcode/LinkedListNew.py

@@ -0,0 +1,158 @@
+class Node:
+    def __init__(self, value):
+        self.value = value
+        self.next = None
+
+class LinkedList:
+    # def __init__(self, value):
+    #     new_node = Node(value)
+    #     self.head = new_node
+    #     self.tail = new_node
+    #     self.length = 1
+    
+    def __init__(self):
+        self.head = None
+        self.tail = None
+        self.length = 0
+    
+    def __str__(self):
+        temp_node = self.head
+        result = ''
+        while temp_node is not None:
+            result += str(temp_node.value)
+            if temp_node.next is not None:
+                result += ' -> '
+            temp_node = temp_node.next
+        return result
+    
+    def append(self, value):
+        new_node = Node(value)
+        if self.head is None:
+            self.head = new_node
+            self.tail = new_node
+        else:
+            self.tail.next = new_node
+            self.tail = new_node
+        self.length += 1
+    
+    def prepend(self, value):
+        new_node = Node(value)
+        if self.head is None:
+            self.head = new_node
+            self.tail = new_node
+        else:
+            new_node.next = self.head
+            self.head = new_node
+        self.length += 1
+    
+    def insert(self, index, value):
+        new_node = Node(value)
+        if self.head is None:
+            self.head = new_node
+            self.tail = new_node
+        elif index == 0:
+            new_node.next = self.head
+            self.head = new_node
+        else:
+            temp_node = self.head
+            for _ in range(index-1):
+                temp_node = temp_node.next
+            new_node.next = temp_node.next
+            temp_node.next = new_node
+        self.length += 1
+    
+    def traverse(self):
+        current = self.head
+        while current is not None:
+            print(current.value)
+            current = current.next
+    
+    def search(self, target):
+        current = self.head
+        while current is not None:
+            if current.value == target:
+                return True
+            current = current.next
+        return False
+    
+    def search(self, target):
+        current = self.head
+        index = 0
+        while current is not None:
+            if current.value == target:
+                return index
+            current = current.next
+            index += 1
+        return -1
+    
+    def get(self, index):
+        if index == -1:
+            return self.tail
+        elif index < -1 or index >= self.length:
+            return None
+        current = self.head
+        for _ in range(index):
+            current = current.next
+        return current
+    
+    def set_value(self, index, value):
+        temp = self.get(index)
+        if temp:
+            temp.value = value
+            return True
+        return False
+    
+    def pop_first(self):
+        if self.length == 0:
+            return None
+        popped_node = self.head
+        if self.length == 1:
+            self.head = None
+            self.tail = None
+        else:
+            self.head = self.head.next
+            popped_node.next = None
+        self.length -= 1
+        return popped_node
+    
+    
+    
+    def pop(self):
+        if self.length == 0:
+            return None
+        popped_node = self.tail
+        if self.length == 1:
+            self.head = self.tail = None
+        else:
+            temp = self.head
+            while temp.next is not self.tail:
+                temp = temp.next
+            temp.next = None
+            self.tail = temp
+        self.length -= 1
+        return popped_node
+    
+
+    def remove(self, index):
+        if index < -1 or index >= self.length:
+            return None
+        if index == 0:
+            return self.pop_first()
+        if index == -1 or index == self.length-1:
+            return self.pop()
+        prev_node = self.get(index-1)
+        popped_node = prev_node.next
+        prev_node.next = popped_node.next
+        popped_node.next = None
+        self.length -= 1
+        return popped_node
+    
+
+linked_list = LinkedList()
+linked_list.append(10)
+linked_list.append(20)
+linked_list.append(30)
+linked_list.append(40)
+print(linked_list)
+print(linked_list.remove(0))
+print(linked_list)