find the stack min

Author: nickolasteixeira

Python/chapter03/3.2 - Stack Min/Nick.py

@@ -0,0 +1,85 @@
+#!/usr/bin/python3
+
+import unittest
+
+
+class Stack:
+    def __init__(self):
+        self.stack = []
+        self.min = None
+
+    def getMin(self):
+        return self.min
+
+    def pop(self):
+        if not self.length:
+            print('No stack to pop')
+            return
+
+        item = self.stack.pop()
+        print('Item popped', item)
+
+        if item == self.min:
+            if self.length() > 0:
+                self.findMin()
+            else:
+                self.min = None
+        return item
+
+    def findMin(self):
+        self.min = self.stack[0]
+        for x in self.stack:
+            if x < self.min:
+                self.min = x
+
+    def length(self):
+        return len(self.stack)
+
+    def push(self, value):
+        if not self.min:
+            self.min = value
+        elif value < self.min:
+            self.min = value
+
+        self.stack.append(value)
+        print('Item added to stack', value)
+
+    def peek(self):
+        if not self.length:
+            print('No stack to peek')
+            return
+        print('Peeking into stack', self.stack[-1])
+
+    def printStack(self):
+        if not self.length:
+            print('No stack to peeek')
+            return
+
+        print("Top of stack\n _ ")
+        for x in self.stack[::-1]:
+            print('|', x, '|')
+            print('|', '_', '|')
+
+
+class Test(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        pass
+
+    @classmethod
+    def tearDownClass(cls):
+        pass
+
+    def test1(self):
+        arr = [2, 5, 7, 10, 3, 10, -1]
+        s = Stack()
+        for x in arr:
+            s.push(x)
+        s.printStack()
+        print('Min value in stack -->', s.getMin())
+        s.pop()
+        print('Min value after pop -->', s.getMin())
+
+
+if __name__ == '__main__':
+    unittest.main()