Python 使用 for 循环创建圣诞树
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Using for loops to create a christmas tree
提问by Sam Procter
I am trying to create a program where you enter a number and the program creates a "christmastree" arrangement of +'s. For example if I enter the number 5 the program should print:
我正在尝试创建一个程序，您可以在其中输入一个数字，然后该程序会创建一个 + 的“圣诞树”排列。例如，如果我输入数字 5，程序应该打印：
+
+++
+++++
+++++++
+++++++++
What I have so far is:
到目前为止我所拥有的是：
def holidaybush(n):
z=n-1
x=1
for i in range(0,n):
for i in range(0,z):
print('',end='')
for i in range(0,x):
print('+',end='')
for i in range(0,z):
print('',end='')
x=x*2
x=x-1
z=z-1
print()
holidaybush(5)
It does not work quite the way I expect, even though I go through the logic and it seems to work in my head. Any help? I just learned for loops today so I may not know everything about them.
它并不像我期望的那样工作，即使我通过了逻辑并且它似乎在我的脑海中工作。有什么帮助吗？我今天刚刚学习了 for 循环，所以我可能不了解它们的一切。
采纳答案by matsjoyce
OK, you have two problems. First, when you go to do your indentation, you write:
好的，你有两个问题。首先，当你进行缩进时，你写：
print('',end='')
In python (and other languages), ''is an empty string. You should use ' '.
在python（和其他语言）中，''是一个空字符串。你应该使用' '.
Second, your xincrementing logic seems to be wrong. Simply adding 2each loop works fine, making your program:
其次，你的x递增逻辑似乎是错误的。只需添加2每个循环就可以正常工作，使您的程序：
def holidaybush(n):
z=n-1
x=1
for i in range(0,n):
for i in range(0,z):
print(' ',end='')
for i in range(0,x):
print('+',end='')
for i in range(0,z):
print(' ',end='')
x=x+2
z=z-1
print()
holidaybush(5)
Your code can be made more compact by:
您的代码可以通过以下方式变得更紧凑：
- Using infix operators, replacing
x=x+2withx+=2 rangeautomatically starts at zero, sorange(0,z)can be replaced withrange(z)- Using string multiplication, replacing your inner
forloops with' ' * z
- 使用中缀运算符，替换
x=x+2为x+=2 range自动从零开始，因此range(0,z)可以替换为range(z)- 使用字符串乘法，
for用' ' * z
Applying these results in:
将这些结果应用于：
def holidaybush(n):
z = n - 1
x = 1
for i in range(n):
print(' ' * z + '+' * x + ' ' * z)
x+=2
z-=1
holidaybush(5)
But you might want to stick with the verbose version.
但您可能想坚持使用详细版本。
回答by Ejaz
how about this:
这个怎么样：
def holidaybush(n):
for i in range(n):
print ' ' * (n - (i + 1)),'+' * (2*i+1)
holidaybush(5)
回答by Alex J Watts
If you change the 'x+=2' to 'x+=1' you get the right shape, but not as many '+', but it won't be as wide mod:
如果您将 'x+=2' 更改为 'x+=1'，您会得到正确的形状，但没有那么多的 '+'，但它不会那么宽：
def holidaybush(n):
z = n
x =1
for i in range(n):
print(' ' * z + '+' * x + ' ' * z)
x+=1
z-=1
holidaybush(5)
回答by Strap
You could use string.center(), just for adding another solution, this made the code more compact:
您可以使用string.center(), 只是为了添加另一个解决方案，这使代码更加紧凑：
def holidaybush(n):
for i in range(n):
print(("+" * (i * 2 + 1)).center(n * 2 - 1))
holidaybush(5)
回答by user9156169
height = eval(input("Enter height of tree: "))
for row in range(height):
for count in range(height - row):
print(end=" ")
for count in range(2*row + 1):
print(end="*")
print()
回答by Chuanyui Teh
We can also do it without any numbers, just for fun
我们也可以不用任何数字来做，只是为了好玩
n = int(input("how big?\t"))
for i in range(n):
for j in range(n-i):
print(' ', end='')
print('\b', end='') #cheating
for k in range(i+n-j):
print('*', end='')
print('')
回答by TT Chowder
number = -1
Range = int(input("how many layers do you want the tree?"))
for x in range(0,Range):
number = number + 2
print(" " * (Range - x), "+" * number)
This worked for me.
这对我有用。
回答by danish hasan
`
`
a=7
n=7
for i in range(7):
print(" "*a,end="")
print("*"*(2*i+1))
a-=1
for b in range (n//2):
print(" *****")
` try this simple code to print the tree using for loop
` 试试这个简单的代码来使用 for 循环打印树
回答by user8334196
This is the very simplest code to draw Christmas tree:
这是绘制圣诞树的最简单代码：
for i in range(1,20,2):
print(('*'*i).center(20))
for leg in range(3):
print(('||').center(20))
print(('\====/').center(20))
