第二次推送时具有自定义比较器分段错误的优先级队列 [英] Priority queue with custom comparator segmentation fault when pushing second time

问题描述

我正在使用 priority_queue ，这是代码:

I'm using a priority_queue, this is the code:

typedef vector<int> state;
typedef bool (*comp)(const state&, const state&);
typedef priority_queue<state, vector<state>, comp> prioq;

prioq prio;

我使用的是自定义比较器，定义在这里:

I'm using a custom comparator, that is defined here:

bool comparator (const state& a , const state& b) {
    return a[0] < b[0];
}

我可以推送第一种状态，但是当我尝试推送第二种状态时，会出现分段错误:11.

I can push the first state, but when I try to push the second, I get a segmentation fault: 11.

我不知道比较器是否正确，我也不知道如何创建自定义比较器.我正在尝试按每个州的第一个数字对 priority_queue 进行排序.

I don't know if the comparator is right, I don't know really much how to create a custom comparator. I'm trying to order the priority_queue by the first number of each state.

推荐答案

prioq prio; 使用默认构造的比较器(类型为 comp )构建优先级队列案件).这意味着内部存储的指向比较函数的指针实际上是用零初始化的.可以将比较器(如果没有默认构造的比较器)初始化为作为构造函数的参数传递的值:

prioq prio; constructs a priority queue with a default-constructed comparator (of type comp in your case). This means that the internally stored pointer to a comparing function is actually initialized with zero. A comparator (if a default constructed one is not enough) can be initialized to a value passed as a constructor's argument:

prioq prio(&comparator);
//         ~~~~~~~~~~^

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