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python - 从 10 反转数字模式。（模式问题）

问题描述

这是我要打印的图案。

1
3 2
6 5 4
10 9 8 7

现在我有一个解决方案，但我不知道它是如何工作的。

解决方案：

length = 6
start = 1
stop = 2
currentNumber = stop
for row in range(stop, length):
    for col in range(start, stop):
        currentNumber -= 1
        print(currentNumber, end=" ")
    print(" ")
    start = stop
    stop += row
    currentNumber = stop

这就是我认为它的工作方式：

# for row in range(2, 6): 2, 3, 4, 5,
# for col in range(1, 2):
#  currentnum = 2-1 = 1
#  print( 1 )
#  start = stop (start = 2)
#  stop += 2 (row = 2,3,4,5) so now stop = 2 + 2 = 4
# currentNumber = 4

# for row in range(4, 6): 4,5
# for col in range(2, 4): 2, 3 means 2 time will loop run
#  currentnum = 4-1 = 3,
#  currentnum = 3-2 = 2
#  print( 3, 2 )
#  start = stop (start = 4)
#  stop += 3 (stro = 4+3 = 7)
#  currentnum = 7

                    **PROBLEM** 

# for row in range(7, 6):    
# for col in range(4, 7): 5,6,7 means 3 time will loop run
#  currentnum = 7-1 = 6,
#  currentnum = 7-2 = 5,
#  currentnum = 7-3 = 4,
#  print( 6, 5, 4)
#  start = stop (start = 7)
#  stop += 3 (stro = 7+3 = 11)
#  currentnum = 11

这是问题（talking from the #commented calculations）：

for i in range(11, 6):
    for j in range(4, 7):
        print("h")
    print("k")
print("j")

由于 (11, 6)，这个 For 循环不会执行。

那就是我的计算出错的地方，我知道我再次不知道这个解决方案是如何工作的。任何人对当前解决方案有更好的解决方案或解释将不胜感激。

只想知道代码是如何工作的

谢谢你。

标签： python

解决方案

我认为您理解的问题是每次停止更改时都重新编写第一个 for 循环。但是，不应该这样做，因为 for 循环只在开始时计算，所以stop一旦它已经在运行，改变变量不应该对循环产生影响，如果这有意义的话。我在这里更正了您的“理解”部分：

#### for loop does not change
# for row in range(2, 6): 2, 3, 4, 5,

### for loop 2 ###
#     for col in range(1, 2):
#         currentNumber -= 1  # 2-1 = 1
#         print(1)
#      start = stop  # (start = 2)
#      stop += 2  # (row currently = 2) so now stop = 2 + 2 = 4
#      currentNumber = 4

### for loop 3 ###
#     for col in range(2, 4): 2, 3 means 2 time will loop run
#         currentnum = 4-1 = 3,
#         currentnum = 3-2 = 2
#         print(3, 2)
#     start = stop  # (start = 4)
#     stop += 3  # (row currently = 3) so now stop = 4 + 3 = 7
#     currentnum = 7

### for loop 4 ###
#     for col in range(4, 7):  # 4, 5, 6 i.e. loop 3 times
#         currentnum = 7-1 = 6,
#         currentnum = 6-1 = 5
#         currentnum = 5 - 1 = 4
#         print(6, 5, 4)
#     start = stop  # (start = 7)
#     stop += 4  # (row currently = 4) so now stop = 7 + 4 = 11
#     currentnum = 11

### for loop 5 ###
#     for col in range(7, 11):  # 7, 8, 9, 10 i.e. loop 4 times
#         currentnum = 11 - 1 = 10
#         currentnum = 10 - 1 = 9
#         currentnum = 9 - 1 = 8
#         currentnum = 8 - 1 = 7
#         print(10, 9, 8, 7)
#     start = stop  # (start = 11)
#     stop += 5  # (row currently = 5) so now stop = 11 + 5 = 16
#     currentnum = 16

希望这是有道理的，但请随时要求澄清。请注意，最后几行无关紧要，因为它是最后一个 for 循环。

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