TheAlgorithms-C/greedy_approach/djikstra.c

#include <stdio.h>
#include <stdlib.h>

#define MAX 20
#define INF 999

int mat[MAX][MAX];
int V;

int dist[MAX];

int q[MAX];
int qp = 0;

void enqueue (int v) {
	q[qp++] = v;
}

int cf (void *a, void *b) {
	int *x = (int *)a;
	int *y = (int *)b;
	return *y - *x;
}

int dequeue () {
	qsort(q, qp, sizeof(int), cf);
	return q[--qp];
}

int queue_has_something () {
	return (qp > 0);
}

int visited[MAX];
int vp = 0;

void dijkstra (int s) {
	dist[s] = 0;
	int i;
	for (i = 0; i < V; ++i) {
		if (i != s) {
			dist[i] = INF;
		}
		enqueue(i);
	}
	while (queue_has_something()) {
		int u = dequeue();
		visited[vp++] = u;
		for (i = 0; i < V; ++i) {
			if (mat[u][i]) {
				if (dist[i] > dist[u] + mat[u][i]) {
					dist[i] = dist[u] + mat[u][i];
				}
			}
		}
	}
}

int main(int argc, char const *argv[]) {

	printf("Enter the number of vertices: ");
	scanf(" %d", &V);
	printf("Enter the adj matrix: ");
	int i, j;
	for (i = 0; i < V; ++i) {
		for (j = 0; j < V; ++j) {
			scanf(" %d", &mat[i][j]);
		}
	}
	
	dijkstra(0);

	printf("\nNode\tDist\n");
	for (i = 0; i < V; ++i) {
		printf("%d\t%d\n", i, dist[i]);
	}
	
	return  0;
}