Q18 Write a program to print tri-diagonal array of given array.

Write a program to print tri-diagonal array of given array.

#include<stdio.h>
#include<conio.h>
void main()
{
int i,j,k;
int mat[5][5]={{1,2,3,4,5},{6,7,8,9,10},
{11,12,13,14,15},{16,17,18,19,20},
{21,22,23,24,25}};
printf("Entered matrix is:\n\n");
for(i=0;i<5;i++)
    {
    for(j=0;j<5;j++)
        {
        printf("%d\t",mat[i][j]);
        }
    printf("\n");
    }
printf("\nTridiagonal matrix:\n\n");
printf("%d\t%d\n",mat[0][0],mat[0][1]);
for(i=1;i<5;i++)
    {
    for(k=1;k<i;k++)
        {
        printf("\t");
        }
    if(i==4)
        printf("%d\t%d\n",mat[4][3],mat[4][4]);
    else
        {
        for(j=i;j<5;j++)
            {
            if(i==j)
            printf("%d\t%d\t%d",mat[i][j-1],
 mat[i][j],mat[i][j+1]);
            }
        printf("\n");
        }
    }
getch();
}

Output

Entered matrix is:

 1       2       3       4       5
 6       7       8       9       10
 11      12      13      14      15
 16      17      18      19      20
 21      22      23      24      25

 Tridiagonal matrix:

 1       2
 6       7       8
         12      13      14
                 18      19      20
                         24      25