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prims.cpp
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prims.cpp
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#include <iostream>
#include <climits>
using namespace std;
int get_min_vertex(bool *visited, int *weight, int n)
{
int min_vertex = -1;
for (int i = 0; i < n; i++)
{
if (!visited[i] && (min_vertex == -1 || (weight[i] < weight[min_vertex])))
{
min_vertex = i;
}
}
return min_vertex;
}
void prims(int **edges, int n)
{
bool *visited = new bool[n];
int *parent = new int[n];
int *weight = new int[n];
for (int i = 0; i < n; i++)
{
weight[i] = INT_MAX;
visited[i] = false;
}
parent[0] = -1;
weight[0] = 0;
for (int i = 0; i < n - 1; i++)
{
int min_vertex = get_min_vertex(visited, weight, n);
visited[min_vertex] = true;
for (int j = 0; j < n; j++)
{
if (!visited[j] && edges[min_vertex][j] != 0)
{
if (weight[j] > edges[min_vertex][j])
{
weight[j] = edges[min_vertex][j];
parent[j] = min_vertex;
}
}
}
}
for (int i = 1; i < n; i++)
{
if (parent[i] < i)
{
cout << parent[i] << " " << i << " " << weight[i] << endl;
}
else
{
cout << i << " " << parent[i] << " " << weight[i] << endl;
}
}
}
int main()
{
int n, e;
cin >> n >> e;
int **edges = new int *[n];
for (int i = 0; i < n; i++)
{
edges[i] = new int[n];
for (int j = 0; j < n; j++)
{
edges[i][j] = 0;
}
}
for (int i = 0; i < e; i++)
{
int f, s, weight;
cin >> f >> s >> weight;
edges[f][s] = weight;
edges[s][f] = weight;
}
prims(edges, n);
for (int i = 0; i < n; i++)
{
delete[] edges[i];
}
delete[] edges;
}