Using two stacks to implement a queue

Using two stacks to implement a queue

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Topic description Use two stacks to implement a queue, complete the queue push and pop operations. The elements in the queue are of type int.

Idea 1 (the most common method):
1, when the queue, directly pressed into the STACK1;
2, out of the team, the first Stack1 all the size-1 elements into the Stack2, and then the elements of the stack1 ejected; Finally, the elements in the Stack2 are re-pressed into the S1.

As shown in the following:

1 classSolution2 {3  Public:4     voidPushintnode) {5 Stack1.push (node);6     }7 8     intpop () {9         intT;Ten          while(Stack1.size () >1){ Onet =stack1.top (); A Stack2.push (t); - Stack1.pop (); -         } the         intRT =stack1.top (); - Stack1.pop (); -          while(Stack2.size () >0){ -t =stack2.top (); + Stack1.push (t); - Stack2.pop (); +         } A         returnRT; at     } -  - Private: -stack<int>Stack1; -stack<int>Stack2; -};

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Idea 2 (Optimization):

1, when the queue, directly pressed into the STACK1;
2, when the team, if the Stack2 is not empty, the direct pop-up, if the Stack2 is empty, the Stack1 size-1 elements are pressed into the Stack2, and finally pop up the stack top element in Stack1.

1 classSolution2 {3  Public:4     voidPushintnode) {5 Stack1.push (node);6     }7 8     intpop () {9         intRT;Ten         if(!Stack2.empty ()) { OneRT =stack2.top (); A Stack2.pop (); -         } -         Else{ the              while(Stack1.size () >1){ -RT =stack1.top (); - Stack2.push (RT); - Stack1.pop (); +             } -RT =stack1.top (); + Stack1.pop (); A         } at         returnRT; -     } - Private: -stack<int>Stack1; -stack<int>Stack2; -};

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Using two stacks to implement a queue