diff --git a/MinStack.java b/MinStack.java
new file mode 100644
index 00000000..b999746f
--- /dev/null
+++ b/MinStack.java
@@ -0,0 +1,36 @@
+class MinStack {
+
+    private int[] stack;
+    private int[] minStack;
+    private int top;
+
+    public MinStack() {
+        stack = new int[30000];
+        minStack = new int[30000];
+        top = -1;
+    }
+
+    public void push(int val) {
+        stack[++top] = val;
+
+        if (top == 0) {
+            minStack[top] = val;
+        } else {
+            minStack[top] = Math.min(val, minStack[top - 1]);
+        }
+    }
+
+    public void pop() {
+        minStack[top] = Integer.MAX_VALUE;
+        stack[top] = Integer.MAX_VALUE;
+        top--;
+    }
+
+    public int top() {
+        return stack[top];
+    }
+
+    public int getMin() {
+        return minStack[top];
+    }
+}
diff --git a/MyHashSet.java b/MyHashSet.java
new file mode 100644
index 00000000..2c70ed9e
--- /dev/null
+++ b/MyHashSet.java
@@ -0,0 +1,53 @@
+class MyHashSet {
+
+    private static final int HASH_SIZE = 78727;   // Chose a very large prime number
+    private static final int BUCKET_SIZE = 70;     // Each bucket size
+
+    private int[][] buckets;
+    private int[] bucketCount;
+
+    public MyHashSet() {
+        buckets = new int[HASH_SIZE][BUCKET_SIZE];
+        bucketCount = new int[HASH_SIZE];
+    }
+
+    private int hash(int key) {
+        return key % HASH_SIZE;
+    }
+
+    public void add(int key) {
+        int h = hash(key);
+
+        // check if exists
+        for (int i = 0; i < bucketCount[h]; i++) {
+            if (buckets[h][i] == key) return;
+        }
+
+        // insert if space available
+        if (bucketCount[h] < BUCKET_SIZE) {
+            buckets[h][bucketCount[h]] = key;
+            bucketCount[h]++;
+        }
+        // if no space space available not inserted but we know 0 <= key <= 10^6
+    }
+
+    public void remove(int key) {
+        int h = hash(key);
+
+        for (int i = 0; i < bucketCount[h]; i++) {
+            if (buckets[h][i] == key) {
+                buckets[h][i] = -1;
+                bucketCount[h]--;
+                return;
+            }
+        }
+    }
+
+    public boolean contains(int key) {
+        int h = hash(key);
+        for (int i = 0; i < bucketCount[h]; i++) {
+            if (buckets[h][i] == key) return true;
+        }
+        return false;
+    }
+}