Dijk.c

#include<stdio.h>

#define infi 999

int mat[20][20], dist[20], path[20];
int n,i,j;
    int q[100];
    int front=-1, rear=-1;

    int isempty()
    {
        if ((front == -1 && rear == -1) || (front > rear))
        {
            front = rear = -1;
            return 1;
        }
        return 0;
    }
    void push(int a)
    {
        if (isempty())
            front++;
        q[++rear] = a;
	    };
    int del()
    {
        return q[front++];
    }



    void input()
    {
      printf("Enter number of nodes:\n");
      scanf("%d", &n);
      printf( "\n\nEnter adjacency matrix\n");
        for (i = 1;i <= n;i++)
        {
	  printf( " enter the weights of row %d : ",i);
            for ( j = 1;j <= n;j++)
	      scanf("%d", &mat[i][j]);
        }
    }
    void init(int m)
    {
        push(m);
	        dist[m] = 0;
        for (i = 1;i <= n;i++)
	        {
            if (i != m)
	            {
                push(i);
	                dist[i] = infi;
            }
            path[i] = 0;
        }
    }
    void min_dist(int m)
    {
        int v, w;
        init(m);
        while (!(isempty()))
        {
            v = del();
            printf( "this is v del %d", v);
            for (i = 1;i <= n;i++)
            {
                if (mat[v][i] != 0)
                {
                    w = i;
                    if ((dist[v] + mat[v][w]) < (dist[w]))
                 {
	                        dist[w] = dist[v] + mat[v][w];
                       path[w] = v;
 
                    }
                }
            }
        }
    }
    void disp_path(int m)
    {
        int p = path[m];
        if (p == 0)
            return;
        disp_path(p);
        printf(" %d",m);
    }
    void disp_dist(int m)
    {
      printf( "Cost: %d", dist[m]);
    }

int main()
{
    int startnode,endnode;
    char answer;

    input();
    do
    {
      printf( "start node: ");
      scanf("%d", &startnode);
        printf( "end node: ");
	scanf("%d", &endnode);
        min_dist(startnode);
        printf("\nFrom %d to %d\n", startnode, endnode);
        printf("------------\n");
        printf("Minimum distance route: (%d", startnode);
        disp_path(endnode);
        printf(")\n");
        disp_dist(endnode);
        printf( "Do you want to calculate another path (Y/N)? ");
        scanf("%c", &answer);
    } while (answer != 'n');
 
}