Design-1 Completed

hashset.py

@@ -0,0 +1,48 @@
+# Uses linked lists to handle hash collisions across 1000 buckets.
+# Each bucket has a dummy head node; add/remove/contains traverse the chain at key % 1000.
+
+# Time Complexity: average per operation O(1)
+# Space Complexity: O(n + k) 
+
+"""
+@author: chinmayprajapati
+"""
+
+class ListNode:
+    def __init__(self, key = -1, next = None):
+        self.key = key
+        self.next = next
+
+class MyHashSet:
+
+    def __init__(self):
+        self.map = [ListNode() for i in range(1000)]
+
+    def hash(self, key):
+        return key % len(self.map)
+
+    def add(self, key: int) -> None:
+        current = self.map[self.hash(key)]
+        while current.next:
+            if current.next.key == key:
+                return
+            current = current.next
+        current.next = ListNode(key)
+
+
+    def remove(self, key: int) -> None:
+        current = self.map[self.hash(key)]
+        while current.next:
+            if current.next.key == key:
+                current.next = current.next.next
+                return 
+            current = current.next
+
+
+    def contains(self, key: int) -> bool:
+        current = self.map[self.hash(key)].next
+        while current:
+            if current.key == key:
+                return True
+            current = current.next
+        return False    

minstack.py

@@ -0,0 +1,32 @@
+# Time Complexity: O(1)
+# Space Complexity: O(n) 
+# Two stacks: one for values, one tracking the running min at each push
+
+"""
+@author: chinmayprajapati
+"""
+
+class MinStack:
+
+    def __init__(self):
+        self.minstack = list()
+        self.stack = list()
+
+    def push(self, val: int) -> None:
+        self.stack.append(val)
+        if not self.minstack:
+            self.minstack.append(val)
+        else:
+            self.minstack.append(min(self.minstack[-1],val))
+
+    def pop(self) -> None:
+        self.stack.pop()
+        self.minstack.pop()
+
+    def top(self) -> int:
+        return self.stack[-1]
+
+    def getMin(self) -> int:
+        if self.minstack:
+            return self.minstack[-1]
+