Design-2 Homework Solution

232. Implement Queue using Stacks/MyQueue.java

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+import java.util.*;
+
+class MyQueue {
+
+    Stack<Integer> inStack;
+    Stack<Integer> outStack;
+
+    public MyQueue() {
+
+        this.inStack = new Stack<>();
+        this.outStack = new Stack<>();
+
+    }
+
+    public void push(int x) {
+        inStack.push(x);
+    }
+
+    public int pop() {
+
+        if (outStack.isEmpty() && inStack.isEmpty()) {
+            return -1;
+        }
+
+        peek();
+        return outStack.pop();
+
+    }
+
+    public int peek() {
+
+        if (outStack.isEmpty()) {
+            while (!inStack.isEmpty()) {
+                outStack.push(inStack.pop());
+            }
+        }
+        return outStack.peek();
+    }
+
+    public boolean empty() {
+
+        return inStack.isEmpty() && outStack.isEmpty();
+
+    }
+}
+
+// TC = O(n)
+// SC = O(n)
+
+/**
+ * Your MyQueue object will be instantiated and called as such:
+ * MyQueue obj = new MyQueue();
+ * obj.push(x);
+ * int param_2 = obj.pop();
+ * int param_3 = obj.peek();
+ * boolean param_4 = obj.empty();
+ */

706. Design HashMap/MyHashMap.java

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+import java.util.*;
+
+class MyHashMap {
+
+    int primaryBucket;
+    int secondaryBucket;
+    int[][] storage;
+
+    public MyHashMap() {
+
+        this.primaryBucket = 1000;
+        this.secondaryBucket = 1000;
+        this.storage = new int[primaryBucket +1][];
+
+    }
+
+    public int getPrimaryHash(int key) {
+
+        return key / primaryBucket;
+
+    }
+
+    public int getSecondaryHash(int key) {
+
+        return key % secondaryBucket;
+
+    }
+
+    public void put(int key, int value) {
+
+        int primaryIndex = getPrimaryHash(key);
+
+        if (storage[primaryIndex] == null) {
+            if (primaryIndex == 0) {
+                storage[primaryIndex] = new int[secondaryBucket + 1];
+            } else {
+                storage[primaryIndex] = new int[secondaryBucket];
+            }
+            Arrays.fill(storage[primaryIndex], -1);
+        }
+
+        int secondaryIndex = getSecondaryHash(key);
+        storage[primaryIndex][secondaryIndex] = value;
+
+    }
+
+    public int get(int key) {
+
+        int primaryIndex = getPrimaryHash(key);
+        if (storage[primaryIndex] == null)
+            return -1;
+
+        int secondaryIndex = getSecondaryHash(key);
+        return storage[primaryIndex][secondaryIndex];
+
+    }
+
+    public void remove(int key) {
+
+        int primaryIndex = getPrimaryHash(key);
+        if (storage[primaryIndex] == null)
+            return;
+
+        int secondaryIndex = getSecondaryHash(key);
+        storage[primaryIndex][secondaryIndex] = -1;
+    }
+}
+
+// TC - O(1)
+// SC - O(10^6) //As it is demmand on allocation so actual is O(1)
+
+/**
+ * Your MyHashMap object will be instantiated and called as such:
+ * MyHashMap obj = new MyHashMap();
+ * obj.put(key,value);
+ * int param_2 = obj.get(key);
+ * obj.remove(key);
+ */