Python implementation - queue using stack + hashmap design

README.md

@@ -1,5 +1,8 @@
 # Design-2
 
+Explain your approach in **three sentences only** at top of your code
+
+
 ## Problem 1: (https://leetcode.com/problems/implement-queue-using-stacks/)
 
 

leetcode_232.py

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+'''
+
+# https://leetcode.com/problems/implement-queue-using-stacks/
+# Time Complexity :
+    push  : O(1)
+    pop   : O(1) amortized
+    peek  : O(1) amortized
+    empty : O(1)
+
+# Space Complexity : O(n), where n is the number of elements.
+# Did this code successfully run on Leetcode : Yes
+# Any problem you faced while coding this : NO
+# Tip: tricky part to transfer all the elements to outstack while peek and pop. Always push into instack
+'''
+
+class MyQueue:
+
+    def __init__(self):
+        self.instack = []
+        self.outstack = []
+
+
+    def push(self, x: int) -> None:
+        self.instack.append(x)
+
+    def pop(self) -> int:
+        if not self.outstack:
+            #transfer all to outstack
+            while self.instack:
+                self.outstack.append(self.instack.pop())
+
+        return self.outstack.pop()
+
+
+    def peek(self) -> int:
+        if len(self.outstack) == 0:
+            #transfer all to outstack
+            while self.instack:
+                self.outstack.append(self.instack.pop())
+
+        return self.outstack[-1]
+
+    def empty(self) -> bool:
+        return not self.instack and not self.outstack
+
+
+# Your MyQueue object will be instantiated and called as such:
+# obj = MyQueue()
+# obj.push(x)
+# param_2 = obj.pop()
+# param_3 = obj.peek()
+# param_4 = obj.empty()

leetcode_706.py

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+
+'''
+
+https://leetcode.com/problems/design-hashmap/description/
+# Time Complexity :
+    put  : O(1)
+    get   : O(1) 
+    remove  : O(1)
+
+# Space Complexity : O(n), where n is the number of elements.
+# Did this code successfully run on Leetcode : Yes
+# Any problem you faced while coding this : NO
+# Tip: Use dummy node for managing edge cases for linked list operations
+'''
+
+
+class Node:
+        def __init__(self, key=None, val=None):
+            self.key = key
+            self.val = val
+            self.next = None
+
+
+class MyHashMap:
+
+    def __init__(self):
+        self.primaryBucket = 10000
+        self.hashmap = [None for i in range(10000)]
+
+    def getHash(self, key):
+        return key % self.primaryBucket
+
+    def put(self, key: int, value: int) -> None:
+        index = self.getHash(key)
+
+        if not self.hashmap[index]:
+            self.hashmap[index] = Node()
+            self.hashmap[index].next = Node(key, value)
+            return
+
+        prev = self.getPrev(self.hashmap[index], key)
+
+        if prev.next == None:
+            prev.next = Node(key, value)
+            return
+
+        prev.next.val = value
+        return
+
+    def getPrev(self, head, key):
+        curr = head
+        prev = None
+        while curr is not None and curr.key != key:
+            prev = curr
+            curr = curr.next
+
+        return prev
+
+
+    def get(self, key: int) -> int:
+        index = self.getHash(key)
+
+        if not self.hashmap[index]:
+            return -1
+
+        prev = self.getPrev(self.hashmap[index], key)
+
+        if prev.next == None:
+            return -1
+        else:
+            return prev.next.val
+
+    def remove(self, key: int) -> None:
+        index = self.getHash(key)
+
+        if not self.hashmap[index]:
+            return
+
+        prev = self.getPrev(self.hashmap[index], key)
+        if prev.next is not None:
+            curr = prev.next
+            prev.next = curr.next
+            del curr    
+
+# Your MyHashMap object will be instantiated and called as such:
+# obj = MyHashMap()
+# obj.put(key,value)
+# param_2 = obj.get(key)
+# obj.remove(key)