Done design-1

Exercise_1.py

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+#Design HashSet
+
+# use an array of size 1000, with each elemnt can have another array of 1000 giving us range 10^6 key limit
+# Using the hashing functions as // and % for keeps the time constraints for each operations O(1)
+# as only when collision happens new sub array is initialized, and that to of max length 1000 so avg case is O1
+# space complexity will be in worst case O(n) where n is the keys added
+class MyHashSet:
+
+    def __init__(self):
+        self.primaryArr = [False] * 1001
+
+    def add(self, key: int) -> None:
+        primaryHash = self.primaryHash(key)
+        if self.primaryArr[primaryHash] == False:
+            self.primaryArr[primaryHash] = [False]*1000
+        secondaryHash = self.secondaryHash(key)
+        self.primaryArr[primaryHash][secondaryHash] = True
+
+    def remove(self, key: int) -> None:
+        primaryHash = self.primaryHash(key)
+        secondaryHash = self.secondaryHash(key)
+        if self.primaryArr[primaryHash]:
+            self.primaryArr[primaryHash][secondaryHash] = False
+
+    def contains(self, key: int) -> bool:
+        primaryHash = self.primaryHash(key)
+        secondaryHash = self.secondaryHash(key)
+        if self.primaryArr[primaryHash]:
+            return self.primaryArr[primaryHash][secondaryHash]
+        return False
+
+    def primaryHash(self, key):
+        return key//1000
+
+    def secondaryHash(self, key):
+        return key%1000
+

Exercise_2.py

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+#Design MinStack
+
+# I'm using 2 stack approach, where 1st stack is saving all the items, while the 2nd is saving only 
+# if the new item is smaller than the last minimum item. Then during the pop we check if the removed item
+# from the stack of all items is same as the min, then remove the last elemnt from 2nd stacka and set the minValue
+# to be the top value from the 2nd array. This gives is O(1) time complexity for all operations and O(n) space complexity
+
+class MinStack:
+
+    def __init__(self):
+        self.allItems = []
+        self.minOrderedItems = []
+        self.minItem = None
+
+    def push(self, val: int) -> None:
+        self.allItems.append(val)
+        if self.minItem == None or self.minItem >= val:
+            self.minItem = val
+            self.minOrderedItems.append(val)
+        # elif self.minItem >= val :
+        #     self.minItem = val
+        #     self.minOrderedItems.append(val)
+        # else:
+        #     return
+
+    def pop(self) -> None:
+        poppedItem = self.allItems.pop()
+        if poppedItem == self.minItem:
+            self.minOrderedItems.pop()
+        if len(self.minOrderedItems) > 0:
+            self.minItem = self.minOrderedItems[-1]
+        else:
+            self.minItem = None    
+
+    def top(self) -> int:
+        return self.allItems[-1]
+
+    def getMin(self) -> int:
+        return self.minItem
+
+
+
+
+# Your MinStack object will be instantiated and called as such:
+# obj = MinStack()
+# obj.push(val)
+# obj.pop()
+# param_3 = obj.top()
+# param_4 = obj.getMin()