matrix = [[0 for i in range(50)] for i in range(50)]

matrix[0][0] = 1

row = len(matrix)

col = len(matrix)

i=0

j=0

for k in range(20):

    if i == 0 and j % 2 == 0:

        j += 1

        matrix[i][j] = matrix[i][j-1] + 1

        while j > 0:

            matrix[i+1][j-1] = matrix[i][j] + 1

            i += 1

            j -= 1

    if j == 0 and i % 2 == 1:

        i += 1

        matrix[i][j] = matrix[i-1][j] + 1

        while i > 0:

            matrix[i-1][j+1] = matrix[i][j] + 1

            j += 1

            i -= 1

print(matrix)