completed hashset and minstack

META-INF/MANIFEST.MF

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+Manifest-Version: 1.0
+Created-By: JetBrains Kotlin
+

MinStack.kt

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+// Time Complexity: O(1) on average
+// Space Complexity: O(capacity) where n is the number of elements
+
+class MinStack() {
+
+    private val capacity: Int = 1_000_000
+    private val stack = IntArray(capacity)
+
+    private val mins = IntArray(capacity)
+
+    private var top = -1
+
+    fun push(`val`: Int) {
+        if (top == capacity - 1) {
+            throw StackOverflowError("Stack overflow: capacity=$capacity")
+        }
+        stack[++top] = `val`
+        mins[top] = if (top == 0) `val` else minOf(`val`, mins[top - 1])
+    }
+
+    fun pop() {
+        if (top == -1) {
+            throw NoSuchElementException("Stack underflow: empty stack")
+        }
+        top--
+    }
+
+    fun top(): Int {
+        return stack[top]
+    }
+
+    fun getMin(): Int {
+        return mins[top]
+    }
+}
+
+fun main() {
+    val minStack = MinStack()
+    minStack.push(-2)
+    minStack.push(0)
+    minStack.push(-3)
+    println(minStack.getMin()) // return -3
+    minStack.pop()
+    println(minStack.top())    // return 0
+    println(minStack.getMin()) // return -2
+}

MyHashSet.kt

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+// Time Complexity: O(1) on average for add, remove, and contains operations
+// Space Complexity: O(n) where n is the number of unique elements added to the set
+// Did this code successfully run on Leetcode : Yes
+// Any problem you faced while coding this : No
+class MyHashSet() {
+
+    val arraySize = 1000
+    val buckets: Array<MutableList<Int>> = Array(arraySize) { mutableListOf<Int>() }
+
+    fun hash(key: Int) : Int {
+        return key % arraySize
+    }
+
+    fun add(key: Int) {
+        val index = hash(key)
+
+        if(!buckets[index].contains(key)) {
+            buckets[index].add(key)
+        }
+    }
+
+    fun remove(key: Int) {
+        val index = hash(key)
+        buckets[index].remove(key)
+    }
+
+    fun contains(key: Int): Boolean {
+        val index = hash(key)
+        return buckets[index].contains(key)
+    }
+}
+
+ fun main() {
+    var obj = MyHashSet()
+    obj.add(89)
+    obj.add(122323)
+    obj.add(2)
+    obj.remove(122323)
+    obj.remove(12)
+    println(obj.contains(89))
+ }