c언어로 PQ구현

Priority_queue 구현

1. 연결리스트

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
using namespace std;
 
typedef struct Node {
    int data;
    Node *next;
} Node;
typedef struct Priority_Queue
{
    Node *head;
    int size;
} Priority_Queue;
void InitPQ(Priority_Queue*pq) {
    pq->head = NULL;
    pq->size = 0;
}
bool IsEmpty(Priority_Queue *pq) {
    return pq->head == NULL;
}
void Push(Priority_Queue *pq, int a) {
    Node *new_node = (Node*)malloc(sizeof(Node));
    new_node->data = a;
    new_node->next = NULL;
    pq->size++;
 
    if (IsEmpty(pq)) {
        pq->head = new_node;
    }
    else {
        Node *prev = NULL;
        Node *now = pq->head;
 
        while (now)
        {
            int now_data = now->data;
            if (a > now_data) {//prev와 now사이에 넣을 수 있음
                break;
            }
            prev = now;
            now = now->next;
        }
        if (prev == NULL) {//PQ에 들어가 있는 값중 제일 큼
            new_node->next = now;
            pq->head = new_node;
        }
        else if (now == NULL) {    //들어가 있는 값 중 제일 작음
            prev->next = new_node;
        }
        else {//중간일경우
            prev->next = new_node;
            new_node->next = now;
        }
 
    }
}
int Pop(Priority_Queue *pq) {
    if (IsEmpty(pq)) return -999;
 
    Node *now = pq->head;
    int re = now->data;
    pq->head = now->next;
 
    free(now);
 
    return re;
}
int main() {
    Priority_Queue qu;
 
    
    InitPQ(&qu);
    Push(&qu, 1);
    Push(&qu, 2);
    Push(&qu, 3);
    printf("%d ", Pop(&qu));
    printf("%d ", Pop(&qu));
    printf("%d ", Pop(&qu));
 
    return 0;
}