Han pasado siglos desde que monté el blog, no ecribo nada… que desastre :(

He resuelto un test de prueba para la plataforma codility, espero que si alguien lee esto algún día le sirva de algo, el test es este:

A zero-indexed array A consisting of N integers is given. An equilibrium index of this array is any integer P such that 0 ≤ P < N and the sum of elements of lower indices is equal to the sum of elements of higher indices, i.e.

A[0] + A[1] + … + A[P−1] = A[P+1] + … + A[N−2] + A[N−1].

Sum of zero elements is assumed to be equal to 0. This can happen if P = 0 or if P = N−1.

For example, consider the following array A consisting of N = 8 elements:
A[0] = -1
A[1] = 3
A[2] = -4
A[3] = 5
A[4] = 1
A[5] = -6
A[6] = 2
A[7] = 1
P = 1 is an equilibrium index of this array, because:

•A[0] = −1 = A[2] + A[3] + A[4] + A[5] + A[6] + A[7]

P = 3 is an equilibrium index of this array, because:

•A[0] + A[1] + A[2] = −2 = A[4] + A[5] + A[6] + A[7]

P = 7 is also an equilibrium index, because:

•A[0] + A[1] + A[2] + A[3] + A[4] + A[5] + A[6] = 0

and there are no elements with indices greater than 7.

P = 8 is not an equilibrium index, because it does not fulfill the condition 0 ≤ P < N.

Write a function:

class Solution { public int solution(int[] A); }

that, given a zero-indexed array A consisting of N integers, returns any of its equilibrium indices. The function should return −1 if no equilibrium index exists.

For example, given array A shown above, the function may return 1, 3 or 7, as explained above.

Assume that:

•N is an integer within the range [0..100,000];
•each element of array A is an integer within the range [−2,147,483,648..2,147,483,647].

Complexity:

•expected worst-case time complexity is O(N);
•expected worst-case space complexity is O(N), beyond input storage (not counting the storage required for input arguments).

Elements of input arrays can be modified.

Y la solución con un 100% es esta (me ha costado):


static int Solution2(int[] A)
{
int valorPordefecto = -1;

if (A.Length == 0) { return -1; }

if (A.Length == 1) { return 0; }

if (A.Length == 2)
{
if (A[0] == 0) { return 1; }
if (A[1] == 0) { return 0; }
}

long left = 0;
long right = 0;

left = A[0];

for (int g = 2; g <= (A.Length - 1); g++)
{
right += A[g];
}

if (left == right) { return 1; }

if (right + A[1] == 0) { return 0; }

for (var i = 1; i < A.Length - 1; i++)
{
if (i == A.Length - 2)
{
left = 0;

for (int k = 0; k < A.Length - 1; k++)
{
left += A[k];
}

if (left == 0)
{
return A.Length - 1;
}
else
{
return valorPordefecto;
}
}
left += A[i];

right -= A[i + 1];

if (left == right) { return i + 1; }
}

return valorPordefecto;
}

¡Hola mundoplano!

Bienvenido, este es un blog acerca de música, cupcakes, programación, viajes, deportes, gadgets y cualquier otra cosa sobre las que nos apetezca escribir, que espero que sea bastante a menudo, os dejo una foto da miña terra galega, si podeis ir algún día os aseguro de que no os arrepentiréis.
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