Cargo Stack Operations — Problem Statement & Solution Guide

#include <bits/stdc++.h>
using namespace std;

class CargoStack {
public:
    CargoStack(const vector<int>& init) {
        // The input is given bottom‑to‑top, so we push in order.
        for (int x : init) st.push(x);
    }
    void importCommand(int x) { st.push(x); }
    bool exportCommand(int &out) {
        if (st.empty()) return false;
        out = st.top();
        st.pop();
        return true;
    }
    bool isEmpty() const { return st.empty(); }
private:
    stack<int> st;
};

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n; if(!(cin>>n)) return 0;
    vector<int> init(n);
    for(int i=0;i<n;++i) cin>>init[i];
    CargoStack cs(init);
    int q; cin>>q;
    while(q--) {
        string cmd; cin>>cmd;
        if(cmd=="import") {
            int x; cin>>x; cs.importCommand(x);
        } else { // export
            int val;
            if(cs.exportCommand(val)) cout<<val<<'\n';
            else cout<<"EMPTY"<<'\n';
        }
    }
    return 0;
}

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        List<Integer> init = new ArrayList<>();
        for (int i = 0; i < n; i++) init.add(sc.nextInt());
        Deque<Integer> stack = new ArrayDeque<>(init);
        int q = sc.nextInt();
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < q; i++) {
            String cmd = sc.next();
            if (cmd.equals("import")) {
                int x = sc.nextInt();
                stack.push(x);
            } else { // export
                if (stack.isEmpty()) {
                    sb.append("EMPTY\n");
                } else {
                    sb.append(stack.pop()).append('\n');
                }
            }
        }
        System.out.print(sb.toString());
        sc.close();
    }
}

import sys

def main():
    data = sys.stdin.read().strip().split()
    if not data:
        return
    it = iter(data)
    n = int(next(it))
    init = [int(next(it)) for _ in range(n)]
    stack = init[:]  # bottom to top, last element is top
    q = int(next(it))
    out = []
    for _ in range(q):
        cmd = next(it)
        if cmd == 'import':
            x = int(next(it))
            stack.append(x)
        else:  # export
            if stack:
                out.append(str(stack.pop()))
            else:
                out.append('EMPTY')
    sys.stdout.write('\n'.join(out))

if __name__ == "__main__":
    main()

const fs = require('fs');
const input = fs.readFileSync(0, 'utf8').trim().split(/\s+/);
let idx = 0;
const n = Number(input[idx++]);
const init = [];
for(let i=0;i<n;i++) init.push(Number(input[idx++]));
class CargoStack {
    constructor(arr) { this.stack = [...arr]; }
    importCommand(x) { this.stack.push(x); }
    exportCommand() { return this.stack.pop(); }
    isEmpty() { return this.stack.length===0; }
}
const cs = new CargoStack(init);
const q = Number(input[idx++]);
let out = [];
for(let i=0;i<q;i++) {
    const cmd = input[idx++];
    if(cmd==='import') {
        const x = Number(input[idx++]);
        cs.importCommand(x);
    } else { // export
        if(cs.isEmpty()) out.push('EMPTY');
        else out.push(String(cs.exportCommand()));
    }
}
console.log(out.join('\n'));