TheAlgorithms-C-Plus-Plus/greedy_algorithms/Prims Minimum Spanning Tree.cpp

#include <iostream>
using namespace std;

#define V 4
#define INFINITY 99999

int graph[V][V] = {
	{0, 5, 1, 2},
	{5, 0, 3, 3},
	{1, 3, 0, 4},
	{2, 3, 4, 0}};

struct mst
{
	bool visited;
	int key;
	int near;
};

mst MST_Array[V];

void initilize()
{
	for (int i = 0; i < V; i++)
	{
		MST_Array[i].visited = false;
		MST_Array[i].key = INFINITY; // considering INFINITY as inifinity
		MST_Array[i].near = i;
	}

	MST_Array[0].key = 0;
}

void updateNear()
{
	for (int v = 0; v < V; v++)
	{
		int min = INFINITY;
		int minIndex = 0;
		for (int i = 0; i < V; i++)
		{
			if (MST_Array[i].key < min && MST_Array[i].visited == false && MST_Array[i].key != INFINITY)
			{
				min = MST_Array[i].key;
				minIndex = i;
			}
		}

		MST_Array[minIndex].visited = true;

		for (int i = 0; i < V; i++)
		{
			if (graph[minIndex][i] != 0 && graph[minIndex][i] < INFINITY)
			{
				if (graph[minIndex][i] < MST_Array[i].key)
				{
					MST_Array[i].key = graph[minIndex][i];
					MST_Array[i].near = minIndex;
				}
			}
		}
	}
}

void show()
{
	for (int i = 0; i < V; i++)
	{
		cout << i << "  -  " << MST_Array[i].near << "\t" << graph[i][MST_Array[i].near] << "\n";
	}
}

int main()
{
	initilize();
	updateNear();
	show();
	return 0;
}