A C++ function meant to detect taxicab numbers (sums of two positive cubes in exactly two ways) counts matches with two nested loops and returns count == 2. Find and fix the bug.

A C++ function should return true when x is a taxicab number, a positive integer that is a sum of two positive cubes in exactly two distinct ways (1729 = 1^3 + 12^3 = 9^3 + 10^3). It counts matches with two nested loops over i and j that both start at 1 and stop when the cube reaches x, and returns count == 2. Find the bug and fix it with minimal changes.