PHP two-way queue, dual-end queue code

PHP two-way queue, dual-end queue code

/** * User: jifei * Date: 2013-07-30 * Time: 23: 12 */ /** * PHP implements two-way queues and dual-end queues * A double-ended queue (deque) is a data structure with queues and stacks. * Elements in a dual-end queue can pop up from both ends. the insert and delete operations are limited to both sides of the queue. */ Class Deque { Public $ queue = array (); /** * Constructor initializes the queue. */ Public function _ construct ($ queue = array ()) { If (is_array ($ queue )) { $ This-> queue = $ queue; } } /** * Obtain the first element. */ Public function front () { Return reset ($ this-> queue ); } /** * Obtain the last element. */ Public function back () { Return end ($ this-> queue ); } /** * Determines whether it is null. */ Public function is_empty () { Return empty ($ this-> queue ); } /** * Queue size */ Public function size () { Return count ($ this-> queue ); } /** * Insert to the end */ Public function push_back ($ val) { Array_push ($ this-> queue, $ val ); } /** * Insert to header */ Public function push_front ($ val) { Array_unshift ($ this-> queue, $ val ); } /** * Remove the last element. */ Public function pop_back () { Return array_pop ($ this-> queue ); } /** * Remove the first element. */ Public function pop_front () { Return array_shift ($ this-> queue ); } /** * Clear a queue */ Public function clear () { $ This-> queue = array (); } } // Initialize a two-way queue $ Deque = new Deque (array (1, 2, 3, 4, 5 )); Echo $ deque-> size (). PHP_EOL; Echo $ deque-> is_empty (). PHP_EOL; Echo $ deque-> front (). PHP_EOL; Echo $ deque-> back (). PHP_EOL; Echo PHP_EOL; // Pop-up element test Echo $ deque-> pop_back (). PHP_EOL; Echo $ deque-> pop_front (). PHP_EOL; Echo $ deque-> size (). PHP_EOL; Echo PHP_EOL; $ Deque-> push_back ('A'). PHP_EOL; $ Deque-> push_front (0). PHP_EOL; Echo PHP_EOL; // Insert test Echo $ deque-> front (). PHP_EOL; Echo $ deque-> back (). PHP_EOL; Echo $ deque-> size (). PHP_EOL; Echo PHP_EOL; // Clear the test $ Deque-> clear (); Echo $ deque-> is_empty ();

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