[IMP] Design-2

DesignHashmap.py

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+''' 
+Time Complexity :  Worst case for collision : O(n)
+Space Complexity : O(n)
+Did this code successfully run on Leetcode : Yes
+Any problem you faced while coding this :  No
+'''
+class MyHashMap:
+
+    class Node:
+        def __init__(self, key, value):
+            self.key = key
+            self.value = value
+            self.next = None
+
+    def __init__(self):
+        self.buckets = 1000
+        self.storage = [None] * self.buckets
+
+    def getHash(self, key):
+        return key % self.buckets
+
+    def getPrev(self, head, key):
+        prev = None
+        curr = head
+        while curr and curr.key != key:
+            prev = curr
+            curr = curr.next
+        return prev
+
+    def put(self, key: int, value: int) -> None:
+        index = self.getHash(key)
+        if self.storage[index] is None:
+            self.storage[index] = self.Node(-1, -1)
+            self.storage[index].next = self.Node(key, value)
+            return
+
+        prev = self.getPrev(self.storage[index], key)
+        if prev.next is None:
+            prev.next = self.Node(key, value)
+        else:
+            prev.next.value = value
+
+    def get(self, key: int) -> int:
+        index = self.getHash(key)
+        if self.storage[index] is None:
+            return -1
+        prev = self.getPrev(self.storage[index], key)
+        if prev.next is None:
+            return -1
+        return prev.next.value
+
+    def remove(self, key: int) -> None:
+        index = self.getHash(key)
+        if self.storage[index] is None:
+            return
+        prev = self.getPrev(self.storage[index], key)
+        if prev.next is None:
+            return
+        prev.next = prev.next.next

QueueUsingStack.py

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+''' 
+Time Complexity : O(1)
+Space Complexity : O(n) 
+Did this code successfully run on Leetcode : Yes
+Any problem you faced while coding this :  No
+'''
+
+class MyQueue:
+
+    def __init__(self):
+        self.in_stack = []
+        self.out_stack = []
+        self.size = 0
+
+    def push(self, x: int) -> None:
+        self.size += 1
+        self.in_stack.append(x)
+
+    def pop(self) -> int:
+        if not self.out_stack:
+            while self.in_stack:
+                self.out_stack.append(self.in_stack.pop())
+
+        self.size -= 1
+        return self.out_stack.pop()
+
+    def peek(self) -> int:
+        if not self.out_stack:
+            while self.in_stack:
+                self.out_stack.append(self.in_stack.pop())
+
+        return self.out_stack[-1]
+
+    def empty(self) -> bool:
+        return self.size == 0