如何修复for循环生成发车时间序列的错误？实现正确的20分钟递增

Let's break down what's going wrong with your current code first, then fix it with a cleaner, more reliable approach.

What's Broken in the Original Code #

Your logic has a few key issues that lead to broken time outputs like 15:-4:

• You're printing twice per loop iteration, which creates duplicate or unexpected entries
• The break statement stops the loop entirely when minutes hit 60 instead of carrying over to the next hour
• The minute calculation after attempting to carry over (m = m-60+20) is out of order, leading to negative values when the timing math doesn't line up

The Fix: Use Total Minutes for Clean Carryover #

Instead of manually adjusting hours and minutes separately, convert everything to total minutes since midnight, add your 20-minute interval, then convert back to hours and minutes. This eliminates all edge cases with negative minutes or missed carryovers.

Here's the corrected code:

h = 13
m = 36
# Adjust range(5) if you want more/less departure times
for _ in range(5):
    # Format minutes to 2 digits so times like 15:6 show as 15:06
    print(f"The train will leave at {h}:{m:02d}")
    # Calculate total minutes since midnight, add 20 minutes for the next interval
    total_minutes = h * 60 + m + 20
    # Convert back to hours and minutes (auto-handles carryover)
    h = total_minutes // 60
    m = total_minutes % 60

How This Works #

1. Initialization: Start with your base time (13:36)
2. Print: Output the current formatted time (using :02d ensures minutes are always two digits for proper time formatting)
3. Total Minutes Calculation: Convert hours to minutes, add the current minutes, then add 20 for the next departure interval
4. Convert Back: Use integer division (//) to get the new hour count, and modulus (%) to get the remaining minutes—this automatically handles carryover when minutes exceed 60

Sample Output #

Running this code will produce:

The train will leave at 13:36
The train will leave at 13:56
The train will leave at 14:16
The train will leave at 14:36
The train will leave at 14:56

If you extend the loop, it will correctly output The train will leave at 15:16 next, with no negative minutes or broken logic.

内容的提问来源于stack exchange，提问作者vectorizinglife