# 3.22. Glossary

- algorithm
- a generic, step-by-step list of instructions for solving a problem
- balanced parentheses
- each opening symbol has a corresponding closing symbol and the pairs of parentheses are properly nested
- deque
- empty
- first-in first-out (FIFO)
- empty
- fully parenthesized
- the usage of one pair of parentheses for each operator
- infix
- expression notation in which the operator is in between the two operands that it is working on
- last-in first-out (LIFO)
- ordering principle in which the last item added is also the first removed
- linear data structure
- a data structure with elements that have positions relative to each other
- postfix
- expression notation in which all operators come after the two operands that they work on
- precedence
- hierarchy on the order things occur
- prefix
- expression notation in which all operators precede the two operands that they work on
- stack
- an ordered collection of items where the addition of new items and the removal of existing items always takes place at the same end

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