[백준 1197] 최소 스패닝 트리 (Prim) (C/C++)

#include <stdio.h>
#include <iostream>
#include <vector>
#include <queue>
#include <algorithm>
#include <map>
using namespace std;
 
int V, E;
vector<pair<int, int>> v[10010];
int visited[10010];
int cost;
 
void prim()
{
    priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> pq;
    visited[1] = 1;
    for(int i = 0; i < v[1].size(); i++)
    {
        pq.push({v[1][i].second, v[1][i].first});
    }
    
    while(!pq.empty())
    {
        int now = pq.top().second;
        int nowCost = pq.top().first;        
        pq.pop();
        
        if(visited[now] == 0)
        {
            visited[now] = 1;
            cost += nowCost;
        }
        else
        {
            continue;
        }
        
        for(int i = 0; i < v[now].size(); i++)
        {
            int next = v[now][i].first;
            int nextCost = v[now][i].second;
            
            if(visited[next] == 0)
            {
                pq.push({nextCost, next});
            }
        }
    }
}
 
int main(void)
{
//    freopen("B1197_input.txt", "r", stdin);
    
    cin >> V >> E;
    
    for(int i = 1; i <= E; i++)
    {
        int from, to, weight;
        cin >> from >> to >> weight;
        
        // 양방향 삽입 
        v[from].push_back({to, weight});
        v[to].push_back({from, weight});    
    }
    
    prim();
    
    cout << cost << endl;
    
    return 0;
}