added-stack-min-solution

Chapter-3-Stacks-and-Queues/3.2_stack_min_sol.cpp

@@ -0,0 +1,80 @@
+/*
+ * Cracking the coding interview edition 6
+ * Problem 3-2 : Return the min from a stack.
+ */
+#include<iostream>
+#include<stack>
+#include<utility>
+#include<climits>
+
+using namespace std;
+
+//stack stores the pairs
+//pair.first stores the value
+//pair.second stores the current min element found in the stack
+class minStack{
+private:
+	stack<pair<int,int>> s1;
+
+public:
+	//adds a pair to the top of the stack
+	void push(int x){
+		int currMin=x;
+		if(!isEmpty())
+		{
+		    //check if current element can be minimum of all elements 
+			if(currMin > top().second)
+			{
+			    currMin=top().second;
+			}
+		}
+		s1.push({x,currMin});
+	}
+
+	//pops the stack top pair
+	void pop(){
+		if(isEmpty()){
+			cout<<"Cannot be popped"<<endl;
+			return ;
+		}
+		s1.pop();
+	}
+
+	//returns the current min element in the stack
+	int min(){
+		if(isEmpty()){
+			cout<<"Stack is empty "<<endl;
+			return INT_MAX;   //Maximum value for an object of type int (climits is used)
+		}
+		return s1.top().second;
+	}
+
+	//returns true if stack is empty else false
+	bool isEmpty(){
+		return s1.empty();
+	}
+
+	//returns the stack top pair
+	pair<int,int> top(){
+		if(isEmpty()){
+			return {INT_MAX,INT_MAX};
+		}
+		return s1.top();
+	}
+};
+
+int main(){
+	minStack myStack;
+	pair<int,int> stk;
+	int arr[] = {6, 3, 5, 2, 2, 9, 2, 8, 1, 1};
+	for(int i=0; i<10; i++){
+		myStack.push(arr[i]);
+		cout<<"push in the element "<<arr[i]<<", the current min is "<<myStack.min()<<'\n';
+	}
+	for(int i=0; i<10; i++){
+        stk = myStack.top();
+		myStack.pop();
+		cout<<"pop out the element "<<stk.first<<" from the stack and the current min is "<<myStack.top().second<<'\n';
+	}
+	return 0;
+}