Changed method to matrix that keeps track of min value at all times

NeetCodeRoadmap/Stack/155_Min_Stack.py

@@ -1,53 +1,38 @@
 class MinStack(object):
-
     def __init__(self):
-        self.st=[] #stack
-        self.min=None #min element
+        self.stack = []
 
     def push(self, val):
-        """
-        :type val: int
-        :rtype: None
-        """
-        if len(self.st)==0:
-            self.st.append(val)
-            self.min=val
+        if not self.stack:
+            self.stack.append((val, val))
         else:
-            if val>=self.min:
-                self.st.append(val)
-            else:
-                self.st.append(2*val-self.min)
-                self.min=val
+            mn = min(self.stack[-1][1], val)
+            self.stack.append((val, mn))
+            print(self.stack)
 
     def pop(self):
-        """
-        :rtype: None
-        """
-        x=self.st.pop() 
-        if x<self.min:
-            self.min=2*self.min-x
+        if self.stack:
+            print(self.stack)
+            self.stack.pop()
 
     def top(self):
-        """
-        :rtype: int
-        """
-        x=self.st[-1]
-        if x>=self.min:
-            return x
-        return self.min
-        
+        if self.stack:
+            print(self.stack)
+            return self.stack[-1][0]
+        return 0
 
     def getMin(self):
-        """
-        :rtype: int
-        """
-        return self.min
+        if self.stack:
+            print(self.stack)
+            return self.stack[-1][1]
+        return 0
         
 
 minStack = MinStack()
 minStack.push(-2)
 minStack.push(0)
 minStack.push(-3)
+minStack.push(4)
 minStack.getMin() # return -3
 minStack.pop()
 minStack.top()    # return 0