We have a matrix of integers with m rows and n columns.



We want to calculate the total sum for the matrix:



As you can see, the name "alternating sum" of the title is due to the sign of the terms that changes from one term to its contiguous one and so on.

Let's see an example:
```
matrix = [[1, 2, 3], [-3, -2, 1], [3, - 1, 2]]

total_sum = (1 - 2 + 3) + [-(-3) + (-2) - 1] + [3 - (-1) + 2] = 2 + 0 + 6 = 8
```
You may be given matrixes with their dimensions between these values:```10 < m < 300``` and ```10 < n < 300```.

More example cases in the Example Test Cases.
Enjoy it!!

Difficulty: introductory

Starter code:

def score_matrix(matrix):
	

Solutions:
def score_matrix(matrix):
    return sum((-1) ** (i+j) * matrix[i][j] for i in range(len(matrix)) for j in range(len(matrix[i])))


def score_matrix(matrix):
    return sum(
        (-1)**(i+j) * x
        for i, row in enumerate(matrix)
        for j, x in enumerate(row)
    )

def score_matrix(matrix):
    total_sum = 0
    for (x,row) in enumerate(matrix):
        for (y, v) in enumerate(row):
            total_sum += v * (1 if (x+y)%2 == 0 else -1)
    return total_sum

def score_matrix(matrix):
    return sum(sum(el if (row_idx + col_idx) % 2 == 0 else -el
                   for col_idx, el in enumerate(row))
               for row_idx, row in enumerate(matrix))

score_matrix=lambda m:sum(y*[1,-1][(i+j)&1] for i,x in enumerate(m) for j,y in enumerate(x))

def score_matrix(matrix):
    res=0
    for i in range(len(matrix)):
        for j in range(len(matrix[0])):
            if (i+j)%2==0:
                res+=matrix[i][j]
            else:
                res-=matrix[i][j]
    return res

def score_matrix(matrix):
    return sum(n * (-1)**(i+j) for j, row in enumerate(matrix) for i, n in enumerate(row))


def score_matrix(matrix):
    s = 0
    for i, row in enumerate(matrix):
        for j, v in enumerate(row):
            s += pow(-1, i + j) * v
    return s

e,score_matrix=enumerate,lambda m:sum(c*(-1)**(i+j)for i,l in e(m)for j,c in e(l))