Counting sort initialization of the output array, each take time. Therefore, the time for the whole algorithm is the sum of the times for these steps, . Because it uses arrays of length and , the total space usage of the algorithm is also . For problem instances in which the maximum key value is significantly smaller than the number of items, counting sort can be highly space-efficient, as the only storage it uses other than its input and output arrays is the Count array which uses space . If each item to be sorted is itself an integer, and used as
Gaussian integer form a commutative ring, which is a subring of the field of complex numbers. It is thus an integral domain. When considered within the complex plane, the Gaussian integers constitute the -dimensional integer lattice. The "conjugate" of a Gaussian integer is the Gaussian integer . The "norm" of a Gaussian integer is its product with its conjugate. The norm of a Gaussian integer is thus the square of its absolute value as a complex number. The norm of a Gaussian integer is a nonnegative integer, which is a sum of two squares. Thus a norm cannot be of the form