C++ 自定义结构体的Priority Queue

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比较函数return true 意味着排序需要交换。

#include <iostream>

#include <queue>

#include <vector>

#include <algorithm>

using namespace std;

struct Item {

    int val = ;

    int idx = ;

};

/**

 * want ascending order, if ties, prefer less idx

 * return true if we want swap happen

 *

 */

class Compare {

public:

    bool operator() (const Item &lhs, const Item &rhs) {

        if (lhs.val == rhs.val) {

            return lhs.idx > rhs.idx;

        }

        return lhs.val < rhs.val;

    }

};

int main() {

    Item item1;

    item1.val = ;

    item1.idx = ;

    Item item2;

    item2.val = ;

    item2.idx = ;

    vector<Item> v = {item1, item2};

    priority_queue<Item, vector<Item>, Compare> myPQ(v.begin(),v.end());

    cout << myPQ.top().idx << endl;

    std::sort(v.begin(),v.end(), Compare());

    cout << v[].val << endl;

    return ;

}