列表排序需求：对给定嵌套列表M执行排序操作

Hey there! Let's work through sorting this nested pyramid-style list M you've shared. Since this is a triangular nested structure, there are a few different sorting scenarios you might be aiming for—here are the most common ones with Python implementations:

1. Sort each individual row (sublist) #

If you want to sort the numbers within each row (either ascending or descending), this is straightforward with list comprehensions and Python's built-in sorting functions:

Ascending order #

M = [[75], [95, 64], [17, 47, 82], [18, 35, 87, 10], [20, 4, 82, 47, 65], [19, 1, 23, 75, 3, 34], [88, 2, 77, 73, 7, 63, 67], [99, 65, 4, 28, 6, 16, 70, 92], [41, 41, 26, 56, 83, 40, 80, 70, 33], [41, 48, 72, 33, 47, 32, 37, 16, 94, 29], [53, 71, 44, 65, 25, 43, 91, 52, 97, 51, 14], [70, 11, 33, 28, 77, 73, 17, 78, 39, 68, 17, 57], [91, 71, 52, 38, 17, 14, 91, 43, 58, 50, 27, 29, 48], [63, 66, 4, 68, 89, 53, 67, 30, 73, 16, 69, 87, 40, 31], [4, 62, 98, 27, 23, 9, 70, 98, 7...]]

# Create a new sorted list without modifying the original
sorted_M_asc = [sorted(sublist) for sublist in M]

# Or modify the original list in-place
for sublist in M:
    sublist.sort()

Descending order #

# Create a new list with each sublist sorted in descending order
sorted_M_desc = [sorted(sublist, reverse=True) for sublist in M]

2. Sort all elements globally, then rebuild the pyramid #

If you want to sort every number in the entire structure, then put them back into the original triangular shape (same number of elements per row):

# Flatten the pyramid into a single list of numbers
all_elements = [num for row in M for num in row]
# Sort all elements (ascending by default; add reverse=True for descending)
all_elements.sort()

# Rebuild the pyramid structure
reconstructed_pyramid = []
current_index = 0
# Each row i has i+1 elements (since first row is length 1)
for row_length in range(1, len(M)+1):
    reconstructed_pyramid.append(all_elements[current_index:current_index + row_length])
    current_index += row_length

3. Sort the rows themselves (by sum, average, etc.) #

If you want to reorder the entire rows based on a metric like their total sum or average value:

# Sort rows by their total sum, from largest to smallest
sorted_by_sum = sorted(M, key=lambda row: sum(row), reverse=True)

# Sort rows by their average value, from smallest to largest
sorted_by_avg = sorted(M, key=lambda row: sum(row)/len(row))

If your sorting goal is different from these (like sorting paths through the pyramid for maximum/minimum sum, for example), feel free to clarify the exact behavior you need, and I can adjust the solution!

内容的提问来源于stack exchange，提问作者camarman