Wap to check whether Graph is connected or not using adjacent matrix multiplication.

#include<stdio.h>

#include<conio.h>

int connect();

int d[20][20],a[20][20],n;

int main()

{

    int i,j,flag=0;

    printf("Enter the number of vertices in a graph: ");

    scanf("%d",&n);

    printf("Enter the adjacency matrix:\n");

    for(i=1;i<=n;i++)

    {

       for(j=1;j<=n;j++)

       {

          scanf("%d",&a[i][j]);

          d[i][j]=a[i][j];

       }

    }

    Printf("Adjacency Matrix is:\n");

    for(i=1;i<=n;i++)

      {

          for(j=1;j<=n;j++)

          {    

                            printf( "%d\t",d[i][j]);

                             }

                             printf("\n");

                             }

   for(i=1;i<=n-1;i++)

   {

   

   connect();

}

   printf("Multiplication of matrices is:\n");

   for(i=1;i<=n;i++)

   {

       for(j=1;j<=n;j++)

    {

        printf("%3d",d[i][j]);

      }

      printf("\n");

    }

    for(i=1;i<=n;i++)

    {

       for(j=1;j<=n;j++)

       {

       if(d[i][j]==0)

       flag=1;

   

    }

   

    }

    if(flag==0)

    {

   printf("connected");

    }

else

{

    printf("disconnected");

}

    getch();

}

int connect()

{

    int i,j,k,c[20][20]={0};  

   

         for(i=1;i<=n;i++)

    {

                       for(j=1;j<=n;j++)

                       {             

         for(k=1;k<=n;k++)

         {

            c[i][j]=c[i][j]+(d[i][k]*a[k][j]);

         }  

       }

   

     }

     for(i=1;i<=n;i++)

    {

                       for(j=1;j<=n;j++)

                       {    

                             d[i][j]=c[i][j];

                             }

                             }

                           

}