def test_pop_two_element(self): stack = Stack() stack.push(1) stack.push(2) self.assertEqual(stack.pop(), 2, "We should pop 2") self.assertEqual(stack.peek(), 1) self.assertEqual(stack.size(), 1) self.assertEqual(stack.pop(), 1, "We should pop 1") self.assertEqual(stack.size(), 0)
def is_balanced(brackets): brackets = brackets.strip() if brackets == '': raise Exception("The string is empty") if '(' not in brackets and ')' not in brackets: raise Exception("This string without brackets") stack = Stack() for bracket in brackets: if bracket == ')' and stack.is_empty(): print( "The string is started with closed bracket and it is not balanced" ) return False elif bracket == '(': stack.push(bracket) elif bracket == ')': stack.pop() else: raise Exception("This string has something else but brackets") if stack.is_empty(): print("The string is balanced") return True else: print("The string is not balanced") return False
def test_pop_one_element(self): stack = Stack() stack.push(1) stack.pop() self.assertEqual(stack.tail, None) self.assertEqual(stack.head, None) self.assertEqual(stack.size(), 0)
def calculate_postfix(expression): S = Stack() if not expression: raise Exception("The string is empty") for item in expression: if item.isdigit(): S.push(int(item)) elif item == "+": val1 = S.pop() val2 = S.pop() S.push(val1 + val2) elif item == "*": val1 = S.pop() val2 = S.pop() S.push(val1 * val2) elif item == "-": val1 = S.pop() val2 = S.pop() S.push(val1 - val2) elif item == "/": val1 = S.pop() val2 = S.pop() S.push(val1 / val2) elif item == "=": return S.pop() return S.pop()
def __init__(self): Stack.__init__(self)
def size(self): return Stack.size(self)
def getTail(self): return Stack.get_tail(self)
def getFront(self): return Stack.get_head(self)
def removeTail(self): return Stack.pop(self)
def addTail(self, item): Stack.push(self,item)
def test_stack_peek(self): stack = Stack() stack.push(77) stack.push(123) self.assertEqual(stack.peek(), 123, "We should peek 123") self.assertEqual(stack.pop(), 123, "We hsould pop 123") self.assertEqual(stack.peek(), 77, "We should peek 77") self.assertEqual(stack.pop(), 77, "We should pop 77") self.assertEqual(stack.size(), 0) self.assertIsNone(stack.peek(), "peek is none")
def test_peek_empty(self): stack = Stack() self.assertIsNone(stack.peek(), "peek is none")
def enqueue(self, item): #need to add element to the end of the list Stack.push(self, item)
def __init__(self): Stack.__init__(self) #initialize with stack end