4.8 KiB
4.8 KiB
id | title | challengeType | forumTopicId | localeTitle |
---|---|---|---|---|
587d8250367417b2b2512c5f | Create a Stack Class | 1 | 301633 | Создать класс стека |
Description
push
и pop
, у стеков есть и другие полезные методы. Давайте добавим peek
, isEmpty
и clear
метод в наш класс стека. Инструкции Напишите метод push
который подталкивает элемент к вершине стека, метод pop
который удаляет элемент в верхней части стека, метод peek
который смотрит на первый элемент в стеке, метод isEmpty
который проверяет, стек пуст и clear
метод, который удаляет все элементы из стека. Обычно у стеков это не так, но мы добавили метод вспомогательной print
котором консоль регистрирует коллекцию.
Instructions
push
method that pushes an element to the top of the stack, a pop
method that removes the element on the top of the stack, a peek
method that looks at the first element in the stack, an isEmpty
method that checks if the stack is empty, and a clear
method that removes all elements from the stack.
Normally stacks don't have this, but we've added a print
helper method that console logs the collection.
Tests
tests:
- text: Your <code>Stack</code> class should have a <code>push</code> method.
testString: assert((function(){var test = new Stack(); return (typeof test.push === 'function')}()));
- text: Your <code>Stack</code> class should have a <code>pop</code> method.
testString: assert((function(){var test = new Stack(); return (typeof test.pop === 'function')}()));
- text: Your <code>Stack</code> class should have a <code>peek</code> method.
testString: assert((function(){var test = new Stack(); return (typeof test.peek === 'function')}()));
- text: Your <code>Stack</code> class should have a <code>isEmpty</code> method.
testString: assert((function(){var test = new Stack(); return (typeof test.isEmpty === 'function')}()));
- text: Your <code>Stack</code> class should have a <code>clear</code> method.
testString: assert((function(){var test = new Stack(); return (typeof test.clear === 'function')}()));
- text: The <code>peek</code> method should return the top element of the stack
testString: assert((function(){var test = new Stack(); test.push('CS50'); return (test.peek() === 'CS50')}()));
- text: The <code>pop</code> method should remove and return the top element of the stack
testString: assert((function(){var test = new Stack(); test.push('CS50'); return (test.pop() === 'CS50');}()));
- text: The <code>isEmpty</code> method should return true if a stack does not contain any elements
testString: assert((function(){var test = new Stack(); return test.isEmpty()}()));
- text: The <code>clear</code> method should remove all element from the stack
testString: assert((function(){var test = new Stack(); test.push('CS50'); test.clear(); return (test.isEmpty())}()));
Challenge Seed
function Stack() {
var collection = [];
this.print = function() {
console.log(collection);
};
// Only change code below this line
// Only change code above this line
}
Solution
class Stack {
constructor() {
this.collection = [];
}
print() {
console.log(this.collection);
}
push(val) {
this.collection.push(val);
}
pop() {
return this.collection.pop();
}
peek() {
return this.collection[this.collection.length - 1];
}
isEmpty() {
return this.collection.length === 0;
}
clear() {
return (this.collection.length = 0);
}
}