Find Shortest Path using Dijkstra’s Algorithm

#include <stdio.h>
#include <limits.h>

#define V 9  // Number of vertices in the graph

// Function to find the vertex with the minimum distance value
int minDistance(int dist[], int sptSet[]) {
    int min = INT_MAX, min_index;

    for (int v = 0; v < V; v++) {
        if (sptSet[v] == 0 && dist[v] <= min) {
            min = dist[v];
            min_index = v;
        }
    }
    return min_index;
}

// Function to implement Dijkstra's algorithm
void dijkstra(int graph[V][V], int src) {
    int dist[V];  // Output array. dist[i] holds the shortest distance from src to i
    int sptSet[V]; // Shortest Path Tree Set

    // Initialize all distances as infinite and sptSet as false
    for (int i = 0; i < V; i++) {
        dist[i] = INT_MAX;
        sptSet[i] = 0;
    }

    // Distance from source to itself is always 0
    dist[src] = 0;

    // Find the shortest path for all vertices
    for (int count = 0; count < V - 1; count++) {
        // Pick the minimum distance vertex from the set of vertices not yet processed
        int u = minDistance(dist, sptSet);
        sptSet[u] = 1; // Mark the picked vertex as processed

        // Update dist value of the neighboring vertices of the picked vertex
        for (int v = 0; v < V; v++) {
            // Update dist[v] if and only if it is not in sptSet, there is an edge from u to v,
            // and the total weight of path from src to v through u is smaller than the current value of dist[v]
            if (!sptSet[v] && graph[u][v] && dist[u] != INT_MAX && dist[u] + graph[u][v] < dist[v]) {
                dist[v] = dist[u] + graph[u][v];
            }
        }
    }

    // Print the constructed distance array
    printf("Vertex \t Distance from Source\n");
    for (int i = 0; i < V; i++) {
        printf("%d \t %d\n", i, dist[i]);
    }
}

int main() {
    // Example graph represented as an adjacency matrix
    int graph[V][V] = {
        {0, 4, 0, 0, 0, 0, 0, 8, 0},
        {4, 0, 8, 0, 0, 0, 0, 11, 0},
        {0, 8, 0, 7, 0, 4, 0, 0, 2},
        {0, 0, 7, 0, 9, 14, 0, 0, 0},
        {0, 0, 0, 9, 0, 10, 0, 0, 0},
        {0, 0, 4, 14, 10, 0, 2, 0, 0},
        {0, 0, 0, 0, 0, 2, 0, 1, 6},
        {8, 11, 0, 0, 0, 0, 1, 0, 7},
        {0, 0, 2, 0, 0, 0, 6, 7, 0}
    };

    dijkstra(graph, 0); // Starting from vertex 0

    return 0;
}