Jiudu_topic 1512: queue using two stacks

This idea is too difficult to think about ....

/** STR is push, and elements are pushed into the stack through s1.push (); * When STR is pop, S2 is not empty, the top element of the output stack is displayed, and s2.pop () is the top element of the stack; if the element after S2 pop-up is empty and S1 is not empty, push all elements in S1 into S2; * If STR is pop, S2 is empty. If S1 is not empty, push all elements in S1 to S2, and finally output the top elements of the stack and use <span style = "font-family: Arial, Helvetica, sans-serif;"> s2.pop () the top element of the stack is displayed. </span> ;*/

Description: Two stacks are used to implement a queue and push and pop operations of the queue are completed.
The element in the queue is of the int type.
Input:
Each input file contains a test sample.
For each test example, enter N (1 <= n <= 100000) In the first line, which indicates the number of queue operations.
For the next n rows, enter a queue operation for each row:
1. Push X to push an integer x (x> = 0) to the queue)
2. Pop: the number of POPs in the queue.
Output:
For each test case, print the numbers from the pop in the queue in all pop operations. If the queue is empty during the pop operation, print-1.
Sample input:
3
Push 10
Pop
Pop
Sample output:
10
-1

# Include <iostream> # include <string> # include <stack> using namespace STD;/** STR: Push, s1.push (); * When STR is pop, S2 is not empty, s2.pop () is the top element of the output stack. If S2. if S2. if SS1 is not empty, all elements in S1. * If STR is pop, S2, if S1 is not empty, push all elements in S1 to S2, and finally output the top element of the stack; */INT main () {int N; while (CIN> N) {stack <int> S1, S2; int num; string STR; For (INT I = 0; I <n; I ++) {CIN> STR; if (STR = "push") {CIN> num; s1.push (Num);} else if (STR = "pop") {If (! S2.empty () {cout <s2.top () <Endl; s2.pop (); If (s2.empty () {If (! S1.empty () {While (! S1.empty () {s2.push (s1.top (); s1.pop () ;}}} else {If (s1.empty () {cout <-1 <Endl; continue;} else {While (! S1.empty () {s2.push (s1.top (); s1.pop () ;}} cout <s2.top () <Endl; s2.pop ();}}}}} /*************************************** * *********************** problem: 1512 User: hndxztf language: C ++ result: accepted time: 580 MS memory: 1656 kb ************************************** **************************/

Jiudu_topic 1512: queue using two stacks