/* --------------------------------------------------------------------- 
**  Figure 21.3: A recursive program to find a minimum.
** --------------------------------------------------------------------- 
*/
#include <stdio.h>    
                               
#define N 15
int array_min( int a[], int n );

void main( void )                                                      
{
    int data[N] = { 19, 17, 2, 43, 47, 5, 37, 23, 3, 41, 29, 31, 7, 11, 13 };          
    int answer;   

    printf( "\n Find minimum in an array of %i positive integers.\n", N );  
    answer = array_min( data, N );
    printf( "\n Minimum = %i\n\n", answer );  
}
   
/* -------------------------------------------------------------------- */    
int 
array_min( int a[], int n ) 
{
    int tailmin, answer;
        
    printf( " Entering: n=%2i  head=%2i \n", n, a[0] );

    /* Base case. ---------------------------------------------------- */    
    if (n == 1)  { 
        printf( "  ---- Base case ----\n" );
        answer = a[0];
    }
    /* Recursive step. ----------------------------------------------- */    
    else { 
        tailmin = array_min( &a[1], n - 1 );
        if (a[0] < tailmin) answer = a[0];
        else answer = tailmin;
    }  

    printf( " Leaving:  n=%2i  head=%2i  returning=%2i \n", n, a[0], answer );
    return answer;
}