2021-08-23 11:07:33 +08:00
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# STACK
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stack is an ADT (abstract data type ) that act like list of objects but there is a diffrents.
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2021-09-26 17:26:59 +08:00
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stack act is _LIFO_ (Last In First Out), it means that when we want to get an element from the stack we get the last element in the stack.
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2021-08-23 11:07:33 +08:00
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2021-10-09 00:17:58 +08:00
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stack is based on two methods (functions)
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2021-08-23 11:07:33 +08:00
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2021-10-09 00:17:58 +08:00
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## push(element)
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2021-08-23 11:07:33 +08:00
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2021-10-09 00:17:58 +08:00
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add "element" to the top of the stack.
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2021-08-23 11:07:33 +08:00
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for example: we have `1, 3, 5` in stack, then we call push(9),
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`9` will add to last index of stack -> `1, 3, 5 , 9`
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2021-10-09 00:17:58 +08:00
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## peek() or top()
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return element at the top of the stack.
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for example: we have `1, 3, 5` in stack, then we call peek(),
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`5` will be returned (without removing it from the stack)
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## pop()
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remove the last element (i.e. top of stack) from stack.
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2021-08-23 11:07:33 +08:00
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for example: we have `1, 3, 5 , 9` in stack, then we call pop(),
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the function will return `9` and the stack will change to `1, 3, 5`.
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