Prims

#include <stdio.h>

#include <limits.h>

#define V 6

int minKey(int key[], int mstSet[]) {

    int min = INT_MAX, min_index;

    for (int v = 0; v < V; v++)

        if (!mstSet[v] && key[v] < min)

            min = key[v], min_index = v;

    return min_index;

}

void printMST(int parent[], int graph[V][V]) {

    int total_weight = 0;

    printf("Edge \tWeight\n");

    for (int i = 1; i < V; i++) {

        printf("%c - %c \t%d \n", parent[i] + 'A', i + 'A', graph[i][parent[i]]);

        total_weight += graph[i][parent[i]];

    }

    printf("Total Weight of MST: %d\n", total_weight);

}

void primMST(int graph[V][V]) {

    int parent[V];   // Stores MST

    int key[V];      // Key values

    int mstSet[V];   // Included in MST

    for (int i = 0; i < V; i++)

        key[i] = INT_MAX, mstSet[i] = 0;

    key[0] = 0;       // Start from vertex A

    parent[0] = -1;

    for (int count = 0; count < V - 1; count++) {

        int u = minKey(key, mstSet);

        mstSet[u] = 1;

        for (int v = 0; v < V; v++)

            if (graph[u][v] && !mstSet[v] && graph[u][v] < key[v])

                parent[v] = u, key[v] = graph[u][v];

    }

    printMST(parent, graph);

}

int main() {

    int graph[V][V] = {

        {0, 7, 2, 6, 0, 0},   // A

        {7, 0, 6, 0, 4, 0},   // B

        {2, 6, 0, 6, 9, 0},   // C

        {6, 0, 6, 0, 0, 5},   // D

        {0, 4, 9, 0, 0, 8},   // E

        {0, 0, 0, 5, 8, 0}    // F

    };

    primMST(graph);

    return 0;

}