Completed Design-2

Queue_using_stacks.py

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+// Time Complexity : O(N)
+// Space Complexity : O(N)
+// Did this code successfully run on Leetcode : Yes
+// Any problem you faced while coding this : No
+
+
+// Your code here along with comments explaining your approach
+#I have used two stacks to push all the elements to stack2 when peek method is called and return the top element. 
+#Pop() calls peek() first and then returns top element from stack2.
+
+
+class MyQueue:
+    def __init__(self):
+        self.stack1 = []
+        self.stack2 = []
+
+    def push(self, x:int) -> None:
+        self.stack1.append(x)
+
+    def peek(self) -> int:
+        if self.stack2 == []:
+            while self.stack1:
+                self.stack2.append(self.stack1.pop())
+        return self.stack2[-1]
+
+
+    def pop(self) -> int:
+        self.peek()
+        return self.stack2.pop()
+
+    def empty(self) -> bool:
+        if not self.stack1 and not self.stack2:
+            return True
+        return False

implement_HashMap.py

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+// Time Complexity : O(1)
+// Space Complexity : O(1)
+// Did this code successfully run on Leetcode : Yes
+// Any problem you faced while coding this : No
+
+
+// Your code here along with comments explaining your approach in three sentences only
+#I have designed HashMap using LinkedList that is linear chaining.
+
+class MyHashMap:
+
+    class Node:
+
+        def __init__(self, key, value):
+            self.key = key
+            self.value = value
+            self.next = None
+
+    def __init__(self):
+        self.data = 1000
+        self.storage = [None] * self.data
+
+    def hash1(self, key):
+        index = key % self.data
+        return index
+
+    def findPrev(self, head, key):
+        currentNode = head
+        prev = None
+        while currentNode != None and currentNode.key != key:
+            prev = currentNode
+            currentNode = currentNode.next
+        return prev
+
+    def put(self, key:int, value:int) -> None:
+        data_index = self.hash1(key)
+        if self.storage[data_index] is None:
+            self.storage[data_index] = self.Node(-1,-1)
+        prev = self.findPrev(self.storage[data_index], key)
+        if prev.next is None:
+            prev.next = self.Node(key, value)
+        else:
+            prev.next.value = value
+
+
+    def remove(self, key:int) -> None:
+        data_index = self.hash1(key)
+        if self.storage[data_index] is None:
+            return
+        prev = self.findPrev(self.storage[data_index], key)
+        if prev.next == None:
+            return
+        temp = prev.next
+        prev.next = prev.next.next
+        temp.next = None
+
+    def get(self, key:int) -> int:
+        data_index = self.hash1(key)
+        if self.storage[data_index] is None:
+            return -1
+        prev = self.findPrev(self.storage[data_index], key)
+        if prev.next == None:
+            return -1
+        return prev.next.value
+
+
+