ilovesayyora - 4 months ago 15

C Question

Yes, there are loads of people have already discussed this problem but this one seems to be a bit extraordinary. Program should find the second largest number from the five ones entered by user. We cannot use neither

`loops`

`if`

`arrays`

`goto's`

Input :

`34 -52 87 -12 20`

`34`

Input :

`-87 52 87 87 20`

`87`

As you see user can input two same numbers and program should be able to treat it this way. This is C programming.

`#include <stdio.h>`

#include <stdlib.h>

int main(void)

{

int i1, i2, i3, i4, i5;

int max, second_max;

scanf("%d %d %d %d %d", &i1, &i2, &i3, &i4, &i5);

max = i1;

max = (i2 > max) ? i2 : max;

max = (i3 > max) ? i3 : max;

max = (i4 > max) ? i4 : max;

max = (i5 > max) ? i5 : max;

second_max = i1;

second_max = (i1 > second_max && i1 < max) ? i1 : second_max;

second_max = (i2 > second_max && i2 < max) ? i2 : second_max;

second_max = (i3 > second_max && i3 < max) ? i3 : second_max;

second_max = (i4 > second_max && i4 < max) ? i4 : second_max;

second_max = (i5 > second_max && i5 < max) ? i5 : second_max;

printf("\nmax: %d", max);

printf("\nsecond_max : %d", second_max);

return 0;

}

Here i can find everything, when it comes to the second sample of output it fails. I have an experience of programming but cannot solve this problem since morning

Answer

Clearly, the problem is easy to solve if you can sort the numbers. So how do you sort the numbers using only ternary operators? The answer is known as a sorting network.

Here's what the code looks like:

```
#include <stdio.h>
void swap( int *a, int *b )
{
int x = *a <= *b ? *a : *b;
int y = *a <= *b ? *b : *a;
*a = x;
*b = y;
}
int main( void )
{
int a = 1, b = 9, c = 3, d = 8, e = 3;
swap( &a, &b );
swap( &c, &d );
swap( &b, &e );
swap( &a, &b );
swap( &d, &e );
swap( &a, &c );
swap( &c, &d );
swap( &b, &c );
swap( &c, &d );
printf( "%d %d %d %d %d\n", a,b,c,d,e );
}
```

After the numbers are sorted, the second largest number is `d`

.

Note that if you can't use subroutines and/or pointers, then just copy the body of the `swap`

function and paste it into `main`

nine times. Then change the letters as needed. Have fun with that.