水题,但是我懒得用全局数组实现了,有stl为什么不用。

#include<bits/stdc++.h>
using i64 = long long;

int main() {
    std::cin.tie(nullptr)->sync_with_stdio(false);

    int n, m;
    std::cin >> n >> m;
    std::queue<int> q;
    while (m--) {
        std::string op;
        std::cin >> op;

        if (op == "push") {
            int x;
            std::cin >> x;

            if (q.size() == n) {
                std::cout << "full\n";
            } else {
                q.push(x);
            }
        } else if (op == "front") {
            if (q.empty()) {
                std::cout << "empty\n";
            } else {
                std::cout << q.front() << "\n";
            }
        } else {
            if (q.empty()) {
                std::cout << "empty\n";
            } else {
                std::cout << q.front() << "\n";
                q.pop();
            }
        }
    }

    return 0;
}

https://www.nowcoder.com/discuss/727521113110073344