Find the minimum number in an array with recursion?

Question

int i = 0;
int min = x[i];
while ( i < n ){
 if ( x[i] < min ){
  min = x[i];
 }
 i++;
}
return min;

I've written the iterative form to find the min number of an array. But I'd like to write a function that with recursion. Please help!

Answer 1

Because this sounds like homework, here's a hint: The minimum value in an array is either the first element, or the minimum number in the rest of the array, whichever is smaller.

Answer 2

The minimum number of a single-element array is the one element in the array.

The minimum number of an array with size > 1 is the minimum of the first element and the minimum of the rest of the array.

(The minimum number of an empty array is not defined.)

Answer 3

Why do you want to do this with recursion? A general rule with recursion is don't use recursion if you can do it inside a simple linear loop.

Answer 4

Sounds like homework, but your best bet is something like this:

int main(void) {
    int size = 2;
    int test[] = {0,1};
    int min = test[0];
    findMin(&min, test, size);
    printf("%d", min);
}

void findMin(int* min, int* test, int* length);

void findMin(int* min, int* test, int* length) {
    if (length >= 0) {
         if (*test < *min) {
            *min = test;
         }
         findMin(min, test++, (*length)--);
    }
}

Answer 5

Here is a function that will return a pointer to the minimum value:

#include <stddef.h>

int *recursiveMin(int *x, int n) {
  if (x == NULL || n == 0)
      return NULL;
  if (n == 1)
      return x;
  int *t = recursiveMin(x + 1, n - 1);
  return *x < *t ? x : t;
}

Answer 6

Try:

  int recursive_min(list<int> arr) {
    return recursive_min(arr);
  }

Although this doesn't work in imperative languages.

A more serious answer would be, in pseudocode:

func recursive_min( list l ) {
 head = l[1]
 tail = l[2<->end]
 if l.length==1 return head else return min(head,recursive_min(tail))
}

Although that doesn't work if l is empty.

Answer 7

const int = 20;

int getmin (int v[], int n);

main ()

{ int v[N]; int i,n,min;

printf("\n\tType number of elements:\t"); scanf("%d",&n);

for (i=0;i }

min = getmin (v,n);

printf("\n\n\tMinimume value is %d.",min);

}

int getmin (int v[],int n)

{ if (n>0) {

if ( v[n-2] > v[n-1] )

{ v[n-2]=v[n-1];
}

getmin (v,n-1); }

return v[n-2];
}