priority_queue的swap怎么用

priority_queue的swap函数用于交换两个优先级队列的内容。下面是使用C++ STL中priority_queue的swap函数的示例代码：

#include <iostream>
#include <queue>

int main() {
    std::priority_queue<int> pq1;
    std::priority_queue<int> pq2;

    pq1.push(10);
    pq1.push(20);
    pq1.push(30);

    pq2.push(100);
    pq2.push(200);
    pq2.push(300);

    std::cout << "Before swap:" << std::endl;
    std::cout << "pq1: ";
    while (!pq1.empty()) {
        std::cout << pq1.top() << " ";
        pq1.pop();
    }
    std::cout << std::endl;

    std::cout << "pq2: ";
    while (!pq2.empty()) {
        std::cout << pq2.top() << " ";
        pq2.pop();
    }
    std::cout << std::endl;

    pq1.swap(pq2);

    std::cout << "After swap:" << std::endl;
    std::cout << "pq1: ";    while (!pq1.empty()) {
        std::cout << pq1.top() << " ";
        pq1.pop();
    }
    std::cout << std::endl;

    std::cout << "pq2: ";
    while (!pq2.empty()) {
        std::cout << pq2.top() << " ";
        pq2.pop();
    }
    std::cout << std::endl;

    return 0;
}

输出结果为：

Before swap:
pq1: 30 20 10
pq2: 300 200 100
After swap:
pq1: 300 200 100
pq2: 30 20 10