## Algoritmo de Prim.

Cualquier duda no dudes en contactar.

``````#include <bits/stdc++.h>

using namespace std;

const int MAXN = 100100;
const int INF = 0x3f3f3f3f;

struct edge{
int from, to, weight;
edge(){}
edge(int a, int b, int c){
from = a;
to = b;
weight = c;
}
};

struct state{
int node, dist;
state(){}
state(int a, int b){
node = a; dist = b;
}
bool operator<(const state &other)const{ // sobrecarga de operadores para ordenar
return other.dist < dist;
}
};

vector<edge> graph[MAXN];
bool visited[MAXN]; //No existe en Dijkstra
int dist[MAXN];

int a=1;
int N,E;

int prim(int start){
priority_queue<state> pq;
pq.push(state(start, 0));
dist[start] = 0;
int sum = 0;
while(!pq.empty()){
state cur = pq.top(); pq.pop();
if(dist[cur.node] < cur.dist) continue;
if(visited[cur.node]) continue;
sum += cur.dist;
visited[cur.node] = true;
for(int i=0;i<graph[cur.node].size();i++){
int dest = graph[cur.node][i].to;
int wht = graph[cur.node][i].weight;
if(visited[dest]) continue;
pq.push(state(dest, wht));
dist[dest] = wht;
}
}
return sum;
}

int main(){
freopen("mst.in","r",stdin);
scanf("%d %d",&N,&E);
memset(visited,0,sizeof(visited));
for(int i=1;i<=N;i++) graph[i].clear(); // limpia el grafo
for(int i=0;i<E;i++){
int from, to, weight; scanf("%d %d %d",&from, &to, &weight);
graph[from].push_back(edge(from,to,weight));
graph[to].push_back(edge(to, from, weight)); // borrar linea si es dirigido
}
printf("Prim de %d es %d\n",a,prim(a));
return 0;
}
``````