Implement a queue class that uses two stacks

1/* 2 * implement a queue class. This class uses two stacks to implement 3 * the main difference between queues and stacks is that queues are first-in-first-out, just like in the canteen [for party meals, first-come, first-served 4 * stacks are first-in-first-out, just like bullets in the gun, the first step is to minimize the pressure to 5 * so we only need to modify the peek () and POP () to execute the operation in reverse order, we can use the Second stack to reverse the order of elements 6 *. This approach is feasible, but it is not the most efficient. The elements are removed and moved repeatedly, which is unnecessary. 7 * Here we can delay the movement of elements so that the elements remain in the Second stack, only elements 8*9*10 */11 12 Import Java are moved when the order of elements must be reversed. util. stack; 13 14 public class stacktoqueue <t> {15 stack <t> stacknew, stackold; 16 public stacktoqueue () 17 {18 stacknew = new stack <t> (); 19 stackold = new stack <t> (); 20 21} 22 public int size () 23 {24 return stacknew. size () + stackold. size (); 25} 26 Public void add (T value) // Add elements in the first stack 27 {28 stacknew. push (value); 29} 30 Private void shiftstacks () // reverse the order of implemented elements. elements are extracted from the first stack and placed in the Second stack 31 {32 If (stackold. isempty () 33 {34 while (! Stacknew. isempty () 35 {36 stackold. push (stacknew. pop (); 37} 38} 39} 40 public t PEEK () 41 {42 shiftstacks (); 43 return stackold. peek (); 44} 45 public t remove () 46 {47 shiftstacks (); 48 return stackold. pop (); 49} 50 51 public static void main (string [] ARGs) {52 // todo auto-generated method stub53 stacktoqueue queue = new stacktoqueue (); 54 queue. add (1); 55 queue. add (2); 56 queue. add (3); 57 queue. add (4); 58 queue. add (5); 59 int temp = queue. size (); 60 for (INT I = 0; I <temp; I ++) 61 {62 system. out. println ("Header element:" + queue. remove (); 63} 64 65 66} 67 68}

 

Implement a queue class that uses two stacks