Basic Implementation of min stack bas whenever popping keep an array where you store all previous min and jab bhi min pop then update min with the previous min basic

Author: ChSatyaSavith

155. Min Stack.py

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+class MinStack(object):
+
+    def __init__(self):
+        self.stack = []
+        self.min_arr = []
+        self.min = 2**31
+        self.min_arr.append(self.min)
+    def push(self, val):
+        """
+        :type val: int
+        :rtype: None
+        """
+        if(val<=self.min):
+            self.min = val
+            self.min_arr.append(val)
+        self.stack.append(val)
+
+    def pop(self):
+        """
+        :rtype: None
+        """
+        top = self.stack[len(self.stack)-1]
+        if(top==self.min):
+            self.min_arr.pop()
+            self.min = self.min_arr[len(self.min_arr)-1]
+        return self.stack.pop()
+        
+
+    def top(self):
+        """
+        :rtype: int
+        """
+        return self.stack[len(self.stack)-1]
+        
+
+    def getMin(self):
+        """
+        :rtype: int
+        """
+        if not self.min_arr:
+            return 0
+        return self.min
+        
+
+
+# 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()