From cf536fa73f7a0192777e02235b1a11e268831659 Mon Sep 17 00:00:00 2001
From: mukul <sharmamukul585@gmail.com>
Date: Wed, 24 Dec 2025 21:51:36 +0530
Subject: [PATCH] Done Design-1

---
 HashSet.java  | 64 +++++++++++++++++++++++++++++++++++++++++++++++++++
 MinStack.java | 49 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 113 insertions(+)
 create mode 100644 HashSet.java
 create mode 100644 MinStack.java

diff --git a/HashSet.java b/HashSet.java
new file mode 100644
index 00000000..1f9349e2
--- /dev/null
+++ b/HashSet.java
@@ -0,0 +1,64 @@
+//approach used is double hashing
+//took two arrays one primary and one secondary
+//imlemented hash functions to use in add, remove and contains methods with time complexity of O(1)
+class MyHashSet {
+
+    private boolean storage[][];
+    private int buckets; //length of primary array
+    private int bucketItems;// length of secondary array
+
+    private int hash1(int key){
+        return key%buckets;
+    }
+
+    private int hash2(int key){
+        return key/bucketItems;
+    }
+
+    public MyHashSet() {
+        this.buckets=1000;
+        this.bucketItems=1000;
+        this.storage=new boolean[buckets][];
+    }
+    
+    public void add(int key) { //O(1)
+        int bucket=hash1(key);
+        if(storage[bucket]==null){
+            if(bucket==0){
+                storage[bucket]= new boolean[bucketItems+1];
+            }
+            else{
+            storage[bucket]= new boolean[bucketItems];
+            }
+        }
+        int bucketItem= hash2(key);
+        storage[bucket][bucketItem]=true;
+        
+    }
+    
+    public void remove(int key) { //O(1)
+        int bucket=hash1(key);
+        if(storage[bucket]==null){
+            return;
+        }
+        int bucketItem= hash2(key);
+        storage[bucket][bucketItem]=false;
+    }
+    
+    public boolean contains(int key) { //O(1)
+        int bucket=hash1(key);
+        int bucketItem= hash2(key);
+        if(storage[bucket]==null) return false;
+        return storage[bucket][bucketItem];
+
+        
+    }
+}
+
+/**
+ * Your MyHashSet object will be instantiated and called as such:
+ * MyHashSet obj = new MyHashSet();
+ * obj.add(key);
+ * obj.remove(key);
+ * boolean param_3 = obj.contains(key);
+ */
\ No newline at end of file
diff --git a/MinStack.java b/MinStack.java
new file mode 100644
index 00000000..8386c899
--- /dev/null
+++ b/MinStack.java
@@ -0,0 +1,49 @@
+//Approach was to have a helper stack called minStack
+//Store minimum values in that stack
+//while pushing values in normal stack, we will cpmare values in minStack and then store at the top
+
+class MinStack {
+    
+    Stack <Integer> stack;
+    Stack <Integer> minStack;
+    public MinStack() {
+        stack= new Stack<>();
+        minStack= new Stack<>();
+    }
+    
+    public void push(int val) {
+        //pushes val to normal stack
+        stack.push(val);
+        //we will only push values in minStack if it is empty or value is less than already stored value in minStack
+        if (minStack.isEmpty() || val<=minStack.peek()){
+            minStack.push(val);
+        }
+        
+    }
+    
+    public void pop() {
+        //during pop, we will pop from both stacks
+        int poppedValue= stack.pop();
+
+        if(poppedValue==minStack.peek()){
+            minStack.pop();
+        }
+    }
+    
+    public int top() {
+        return stack.peek();
+    }
+    
+    public int getMin() {
+        return minStack.peek();
+    }
+}
+
+/**
+ * Your MinStack object will be instantiated and called as such:
+ * MinStack obj = new MinStack();
+ * obj.push(val);
+ * obj.pop();
+ * int param_3 = obj.top();
+ * int param_4 = obj.getMin();
+ */
\ No newline at end of file