Algorithm Sedgewick Fourth Edition-1th Chapter Foundation-221 Queuewithtwostacks

1 /******************************************************************************2 * Compilation:javac Queuewithtwostacks.java3 * Execution:java Queuewithtwostacks < Input.txt4 * Dependencies:StdIn.java Stdout.java5 * Data Files:Http://algs4.cs.princeton.edu/13stacks/tobe.txt  6  *7 * A generic queue, implemented using the stacks.8  *9 *% java queuewithtwostacks < tobe.txtTen * To IS or not to is (2 left on queue) One  * A  ******************************************************************************/ -  - Importjava.util.NoSuchElementException; the  -  Public classQueuewithtwostacks<item> { -     PrivateStack<item> Stack1;//Back of the queue -     PrivateStack<item> Stack2;//front of the queue +  -     //Create an empty queue +      Publicqueuewithtwostacks () { AStack1 =NewStack<item>(); atStack2 =NewStack<item>(); -     } -  -     //move all items from Stack1 to Stack2 -     Private voidMovestack1tostack2 () { -          while(!stack1.isempty ()) in Stack2.push (Stack1.pop ()); -     } to  +     //is the queue empty? -      Public BooleanIsEmpty () { the         returnStack1.isempty () &&stack2.isempty (); *     } $ Panax Notoginseng  -     //Return the number of items in the queue. the      Public intsize () { +         returnStack1.size () +stack2.size ();  A     } the  +     //return the item least recently added to the queue. -      PublicItem Peek () { $         if(IsEmpty ())Throw NewNosuchelementexception ("Queue underflow"); $         if(Stack2.isempty ()) Movestack1tostack2 (); -         returnStack2.peek (); -     } the  -     //Add the item to the queueWuyi      Public voidEnqueue (item item) { the Stack1.push (item); -     } Wu  -     //Remove and return the item on the queue least recently added About      PublicItem dequeue () { $         if(IsEmpty ())Throw NewNosuchelementexception ("Queue underflow"); -         if(Stack2.isempty ()) Movestack1tostack2 (); -         returnStack2.pop (); -     } A  +  the     //a test client -      Public Static voidMain (string[] args) { $queuewithtwostacks<string> q =NewQueuewithtwostacks<string>(); the          while(!Stdin.isempty ()) { theString item =stdin.readstring (); the             if(!item.equals ("-") ) Q.enqueue (item); the             Else if(!q.isempty ()) Stdout.print (Q.dequeue () + ""); -         } inStdout.println ("(" + q.size () + "left on queue")); the     } the}

Algorithm Sedgewick Fourth Edition-1th Chapter Foundation-221 Queuewithtwostacks