add new code

Author: msdeep14

Diff for: design-a-stack-that-supports-getmin-in-o1-time-and-o1-extra-space.cpp

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+// https://www.geeksforgeeks.org/design-a-stack-that-supports-getmin-in-o1-time-and-o1-extra-space/
+#include <bits/stdc++.h>
+using namespace std;
+int minEle = INT_MAX;
+void push(stack<int> &s, int x){
+	if(s.empty()){
+		s.push(x);
+		minEle = x;
+		return;
+	}
+	if(x >= minEle){
+		s.push(x);
+	}else{
+		s.push(2*x - minEle);
+		minEle = x;
+	}
+}
+
+void pop(){
+	if(s.empty()){
+		cout << "stack empty\n";
+		return;
+	}
+	int y = s.top();
+	if(y>=minEle){
+		s.pop();
+	}else{
+		minEle = 2*minEle - y;
+		s.pop();
+	}
+}
+
+int main(){
+	int x,y;
+	stack<int> s;
+	while(1){
+		switch(ch){
+			case 1: 
+				cin>>x;
+				push(s,x);
+				break;
+			case 2:
+				pop(s);
+				break;
+			case 3:
+				cout << "min ele is :: " << minEle << endl;
+				break;
+			default:
+				cout << "wrong input \n";
+				break;
+		}
+	}
+	return 0;
+}