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模板 - 优先队列

#include<stdio.h>
#include<algorithm>
#include<queue>
 
using namespace std;
 
struct node{
    int num;
    node(int i){
        num = i;
    }
};
 
priority_queue<node>key;
 
bool operator <(node a ,node b){
    return a.num<b.num;
}
 
 
int main(){
    key.push(node(1));
    key.push(node(4));
    printf("%d\n",key.top().num);
    key.pop();
    key.push(node(2));
    key.push(node(3));
    printf("%d\n",key.top().num);
}
 
 
 
=============================================================================
struct compare {
    bool operator()(const ListNode* l, const ListNode* r) {
        return l->val > r->val;
    }
};
ListNode *mergeKLists(vector<ListNode *> &lists) { //priority_queue
    priority_queue<ListNode *, vector<ListNode *>, compare> q;
    for(auto l : lists) {
        if(l)  q.push(l);
    }
    if(q.empty())  return NULL;

    ListNode* result = q.top();
    q.pop();
    if(result->next) q.push(result->next);
    ListNode* tail = result;           
    while(!q.empty()) {
        tail->next = q.top();
        q.pop();
        tail = tail->next;
        if(tail->next) q.push(tail->next);
    }
    return result;
}
 
 
 

模板 - 优先队列