Completed Design-1 both the questions

Design-1.iml

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+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>

MinStack.java

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+// Time Complexity : O(N)
+// Space Complexity : O(n)
+// Did this code successfully run on Leetcode : yes
+// Any problem you faced while coding this : no
+
+import java.util.*;
+class MinStack {
+
+    // List<Integer> ls;
+    // int size = 0;
+    Stack<Integer> st;  // Stack to store the elements
+    Stack<Integer> minSt; // Stack to store the corresponding minimum elements of the stack elements
+    int min;    // minimum
+
+    public MinStack() {
+        // ls = new ArrayList<>();
+        this.min = Integer.MAX_VALUE;
+        this.st = new Stack<>();
+        this.minSt = new Stack<>();
+        this.minSt.push(this.min); // push to the minimum stack, the maxium integer value to compare with other integer values
+    }
+
+    public void push(int val) {
+        // ls.add(size++, val);
+        st.push(val);
+        min = Math.min(min, val);   //Compare the current element with the previous minimum value
+        minSt.push(min);
+    }
+
+    public void pop() {
+        // ls.remove(--size);
+        st.pop();
+        minSt.pop();    // pop the minimum value
+        min = minSt.peek();
+    }
+
+    public int top() {
+        // return ls.get(size - 1);
+        return st.peek();   // returns value at the top of the stack
+    }
+
+    public int getMin() {
+        // int min = Integer.MAX_VALUE;
+        // for(int item: ls){
+        //     if(item < min){
+        //         min = item;
+        //     }
+        // }
+        // return min;
+
+        return min; // returns minimum value
+    }
+}
+
+/**
+ * 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();
+ */

MyHashSet.java

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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 MyHashSet {
+
+    boolean arr[][]; // pointers
+    int buckets;
+    int bucketItems;
+
+    public MyHashSet() {
+        // arr = new boolean[1000001];
+        this.buckets = 1000; // square root of 1000000
+        this.bucketItems = 1000;
+        this.arr = new boolean[buckets][]; // initialize the pointer with the bucket size
+    }
+
+    public int bucket(int key){
+        return key%buckets; // hashing % to get the bucket
+    }
+
+    public int bucketItem(int key){
+        return key/bucketItems; // hashing / to get the space in the bucket
+    }
+
+    public void add(int key) {
+        // arr[key] = true;
+        int bucket = bucket(key);
+        if(arr[bucket] == null){
+            if(bucket == 0){
+                arr[bucket] = new boolean[bucketItems+1];
+            }else{
+                arr[bucket] = new boolean[bucketItems];
+            }
+        }
+        int bucketItem = bucketItem(key);
+        arr[bucket][bucketItem] = true;
+    }
+
+    public void remove(int key) {
+        // arr[key] = false;
+        int bucket = bucket(key);
+        if(arr[bucket] == null){
+            return;
+        }
+        int bucketItem = bucketItem(key);
+        arr[bucket][bucketItem] = false;
+    }
+
+    public boolean contains(int key) {
+        // return arr[key];
+        int bucket = bucket(key);
+        if(arr[bucket] == null){
+            return false;
+        }
+        int bucketItem = bucketItem(key);
+        return arr[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);
+ */