Completed Design-1

MinStack.java

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+// Time Complexity : push: O(1)
+//                   pop: O(1)
+//                   getMin:O(1)
+//                   top: O(1)
+// Space Complexity :Constructor O(n)
+//                   add: O(1)
+//                   remove: O(1)
+//                   contains:O(1)
+// Did this code successfully run on Leetcode : yes
+// Any problem you faced while coding this : no
+
+import java.util.Stack;
+
+class MinStack {
+    Stack<Integer> stk;
+    int min;
+
+    public MinStack() {
+        this.stk=new Stack<>();
+        this.min = Integer.MAX_VALUE;
+        stk.push(min);
+    }
+
+    public void push(int val) {
+        if(val<=min){
+            stk.push(min);
+            min = val;
+        }
+        stk.push(val);
+    }
+
+    public void pop() {
+        if(min==stk.pop()){
+            min = stk.pop();
+        }
+    }
+
+    public int top() {
+       return stk.peek();
+    }
+
+    public int getMin() {
+            return min ;
+    }
+
+    public static void main(String[] args) {
+        MinStack s = new MinStack();
+        s.push(10);
+        s.push(5);
+        s.push(20);
+        s.push(25);
+        s.push(30);
+        s.pop();
+        System.out.println(s.top() + " is top element of the stack");
+        System.out.println(s.getMin() + " is minimum element of the stack");
+    }
+}

MyHashSet.java

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+// Time Complexity : add: O(1)
+//                   remove: O(1)
+//                   contains:O(1)
+// Space Complexity :Constructor O(n)
+//                   add: O(1)
+//                   remove: O(1)
+//                   contains:O(1)
+// Did this code successfully run on Leetcode : yes
+// Any problem you faced while coding this : (initially I was not understanding remove function
+//                                              then when I debugged it I understood its making the key as false even though its false already as i want to print it i changed the code accordingly)
+
+class MyHashSet {
+    int pBucket;
+    int sBucket;
+    boolean[][] storage;
+
+    public MyHashSet() {
+        this.pBucket=1000;  //square root of 1000000
+        this.sBucket=1000;  //square root of 1000000
+        this.storage= new boolean[pBucket][];
+    }
+
+    //adding a key to the HashSet
+    public void add(int key) {
+        int pIndex = key % pBucket;
+        if(storage[pIndex]==null){
+            if(pIndex == 0){
+                storage[pIndex]= new boolean[sBucket+1];
+            } else {
+                storage[pIndex]= new boolean[sBucket];
+            }
+        }
+        int sIndex= key/sBucket;
+        storage[pIndex][sIndex]=true;
+        System.out.println(key+" added to MyHashSet");
+    }
+
+    //adding a key to the HashSet
+    public void remove(int key) {
+        int pIndex = key % pBucket;
+        if(storage[pIndex]==null){
+           System.out.println(key+" doesn't exists in MyHashSet");
+           return;
+        }
+        int sIndex= key/sBucket;
+        if(storage[pIndex][sIndex]){
+            storage[pIndex][sIndex]=false;
+            System.out.println(key+" is removed from the MyHashSet");
+        } else {
+            System.out.println(key+" doesn't exists in MyHashSet");
+        }
+    }
+
+    //To check whther hashset contains  a key
+    public boolean contains(int key) {
+        int pIndex = key % pBucket;
+        if(storage[pIndex]==null){
+            return false;
+        }
+        int sIndex= key/sBucket;
+         return storage[pIndex][sIndex];
+    }
+
+
+    public static void main(String[] args) {
+        /* Start with the empty list. */
+        MyHashSet hashSet = new MyHashSet();
+
+        hashSet.add(2001);
+        hashSet.add(1000000);
+        hashSet.add(2002);
+        hashSet.add(2);
+        hashSet.add(5);
+        hashSet.add(7);
+        hashSet.add(10);
+        hashSet.add(89);
+        hashSet.add(90);
+
+        hashSet.remove(10);
+        hashSet.remove(2002);
+        hashSet.remove(2005);
+
+        int key =2001;
+        if (hashSet.contains(key)) {
+            System.out.print("My hashSet contains "+ key);
+        } else {
+            System.out.print("My hashSet doesn't contain "+ key);
+        }
+    }
+}
+
+