solved: LeetCode #155 Min Stack on neetcode -@iamserda

neetcodeio/algostructybeginners/Lv1-Arrays/min_stack.py

@@ -2,32 +2,35 @@ class MinStack:
 
     def __init__(self):
         self.stack = []
-        self.min_stack = []
-    
+        self.minstack = []
+
     def push(self, val: int) -> None:
-        self.stack.append(val)
-        if self.min_stack and val < self.min_stack[-1]:
-            popped = self.min_stack.pop()
-            self.min_stack.append(val)
-            self.min_stack.append(popped)
-        else:
-            self.min_stack.append(val)
-
+        if val is not None:
+            self.stack.append(val)
+            if not self.minstack:
+                self.minstack.append(val)
+            elif val < self.minstack[-1]:
+                self.minstack.append(val)
+            else:
+                self.minstack.append(self.minstack[-1])
+
     def pop(self) -> None:
         if self.stack:
-            popped = self.stack.pop()
-        self.min_stack.pop() if popped == self.min_stack[-1] else None
-    
+            self.stack.pop()
+            self.minstack.pop()
+
     def top(self) -> int:
-
+        if self.stack:
+            return self.stack[-1]
 
     def getMin(self) -> int:
-
+        if self.stack:
+            return self.minstack[-1]
 
 
 # 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()
+# param_4 = obj.getMin()