algorithm/back_10845.cpp at master · JuJangGwon/algorithm · GitHub

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#include<iostream>
#include<queue>
#include<string>

using namespace std;

int main(void){

    int N;
    cin >> N;

    queue<int> q;
    int num;

    for(int i=0; i<N; i++){
        string str;
        cin >> str;

        if(str == "push"){
            int data;
            cin >> data;
            q.push(data);

        }else if(str == "pop"){

            if(q.size() != 0){
                num = q.front();
                q.pop();
            }else{
                num = -1;
            }
            cout << num << endl;

        }else if(str == "size"){
            cout << q.size() << endl;

        }else if(str == "empty"){
            if(q.size() == 0) num =1;
            else num =0;
            cout << num << endl;

        }else if(str == "front"){
            if(q.size() == 0){
                num = -1;
            }else{
                num = q.front();
            }
            cout << num << endl;

        }else if(str == "back"){
            if(q.size() == 0){
                num = -1;
            }else{
                num = q.back();
            }
            cout << num << endl;
        }

    }
    return 0;
}