Min stack Design

minStackDesignDay2.js

@@ -0,0 +1,66 @@
+
+/**
+ * I am using two stacks here
+ * One to track the values that we are pushing and popping, The other one is to track the minVal at that point of time.
+ * Reduced more space by pushing the minVal into minStack if and only if the current val that we are pushing into stack is less than the minStack peek val.
+ * 
+ */
+
+class MinStack {
+    constructor(){
+        this.minVal = Infinity;
+        this.stack = [];
+        this.minStack = [];
+        this.minStack.push(this.minVal);
+    }
+    };
+
+    /** 
+     * @param {number} val
+     * @return {void}
+     */
+    MinStack.prototype.push = function(val) {
+       // compare the incoming value with the minVal and update the minVal if needed
+       if(val <= this.minVal){
+        this.minVal = val;
+        // push the minVal on the minStack
+       this.minStack.push(val);
+       }
+       // push the val on to stack
+       this.stack.push(val);
+    };
+
+    /**
+     * @return {void}
+     */
+    MinStack.prototype.pop = function() {
+        const currVal = this.stack.pop();
+        if(currVal === this.getMin()){
+        this.minStack.pop();
+        }
+        this.minVal = this.minStack[this.minStack.length - 1];
+        return currVal;
+    };
+
+    /**
+     * @return {number}
+     */
+    MinStack.prototype.top = function() {
+        return this.stack[this.stack.length - 1];
+    };
+
+    /**
+     * @return {number}
+     */
+    MinStack.prototype.getMin = function() {
+        return this.minStack[this.minStack.length - 1];
+    };
+
+    /** 
+     * Your MinStack object will be instantiated and called as such:
+     * var obj = new MinStack()
+     * obj.push(val)
+     * obj.pop()
+     * var param_3 = obj.top()
+     * var param_4 = obj.getMin()
+     */