最小化嵌套循环

matrix = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
]

total_sum = 0
for i in range(len(matrix)):
    for j in range(len(matrix[i])):
        total_sum += matrix[i][j]
print(total_sum)

matrix = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
]

total_sum = sum(sum(row) for row in matrix)
print(total_sum)

import concurrent.futures

def sum_row(row):
    return sum(row)

matrix = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
]

with concurrent.futures.ThreadPoolExecutor() as executor:
    results = list(executor.map(sum_row, matrix))
total_sum = sum(results)
print(total_sum)