Completes all test cases

NeetCodeRoadmap/Stack/155_Min_Stack.py

@@ -0,0 +1,63 @@
+class MinStack(object):
+
+    def __init__(self):
+        self.st=[] #stack
+        self.min=None #min element
+
+    def push(self, val):
+        """
+        :type val: int
+        :rtype: None
+        """
+        if len(self.st)==0:
+            self.st.append(val)
+            self.min=val
+        else:
+            if val>=self.min:
+                self.st.append(val)
+            else:
+                self.st.append(2*val-self.min)
+                self.min=val
+
+    def pop(self):
+        """
+        :rtype: None
+        """
+        x=self.st.pop() 
+        if x<self.min:
+            self.min=2*self.min-x
+
+    def top(self):
+        """
+        :rtype: int
+        """
+        x=self.st[-1]
+        if x>=self.min:
+            return x
+        return self.min
+        
+
+    def getMin(self):
+        """
+        :rtype: int
+        """
+        return self.min
+        
+
+minStack = MinStack()
+minStack.push(-2)
+minStack.push(0)
+minStack.push(-3)
+minStack.getMin() # return -3
+minStack.pop()
+minStack.top()    # return 0
+minStack.getMin() # return -2
+
+
+
+# Your MinStack object will be instantiated and called as such:
+# obj = MinStack()
+# obj.push(val)
+# obj.pop()
+# param_3 = obj.top()
+# param_4 = obj.getMin()