How to know that a triangle triple exists in our array?

Question

I was stuck in solving the following interview practice question:
I have to write a function:

int triangle(int[] A);

that given a zero-

Answer 1

A 100/100 php solution: http://www.rationalplanet.com/php-related/maxproductofthree-demo-task-at-codility-com.html

function solution($A) {
    $cnt = count($A);
    sort($A, SORT_NUMERIC);
    return max($A[0]*$A[1]*$A[$cnt-1], $A[$cnt-1]*$A[$cnt-2]*$A[$cnt-3]);
}