C program to print following pattern

ABCDEFEDCBA
ABCDE.EDCBA
ABCD      DCBA
ABC           CBA
AB                 BA
A                      A


void main()
{
int i,j,k;
for(i=5;i>=1;i--)
{
for(j=1;j<=5;j++)
{
if(j<=i)
printf("%c",'A' + j-1);
else
printf(" ");
}
for(j=4;j>=1;j--)
{
if(j<=i)
printf("%c",'A' + j-1);
else
printf(" ");
}
printf("\n");
}
}

Square 1 to 100 pattern in C

1   2   3   4   5   6   7   8   9   10
36  37  38  39  40  41  42  43  44  11
35  64  65  66  67  68  69  70  45  12
34  63  84  85  86  87  88  71  46  13
33  62  83  96  97  98  89  72  47  14
32  61  82  95  100 99  90  73  48  15
31  60  81  94  93  92  91  74  49  16
30  59  80  79  78  77  76  75  50  17
29  58  57  56  55  54  53  52  51  18
28  27  26  25  24  23  22  21  20  19

#include<stdio.h> 

int main()
{
    int a[10][10]={0},i,j,low=0,top=9,n=1;
    for(i=0;i<5;i++,low++,top--)
    {
        for(j=low;j<=top;j++,n++)
            a[i][j]=n;
        for(j=low+1;j<=top;j++,n++)
            a[j][top]=n;
        for(j=top-1;j>=low;j--,n++)
            a[top][j]=n;
        for(j=top-1;j>low;j--,n++)
            a[j][low]=n;
    }
    printf("\t\t\t\tPerfect Square\n");
    for(i=0;i<10;i++)
    {
        printf("\n\n\t");
        for(j=0;j<10;j++)
        {
            printf("%6d",a[i][j]);
            delay(300);
        }
    }
    return 0;
}