100 个 Python 小例子（练习题三）

目录

• 实例051：按位与
• 实例052：按位或
• 实例053：按位异或
• 实例054：位取反、位移动
• 实例055：按位取反
• 实例056：画圈
• 实例057：画线
• 实例058：画矩形
• 实例059：画图（丑）
• 实例060：字符串长度
• 例061：杨辉三角
• 实例062：查找字符串
• 实例063：画椭圆
• 实例64：画椭圆、矩形
• 实例065：画组合图形
• 实例066：三数排序
• 实例067：交换位置
• 实例068：旋转数列
• 实例069：报数
• 实例070：字符串长度II
• 实例071：输入和输出
• 实例072：创建链表
• 实例073：反向输出链表
• 实例074：列表排序、连接
• 例075：不知所云

前期练习：

100 个 python 小例子（练习题二）

100 个 Python 小例子（练习题一）

实例051：按位与

题目：学习使用按位与 & 。

程序分析：0&0=0; 0&1=0; 1&0=0; 1&1=1。

a=0o77
print(a)
b=a&3
print(b)
b=b&7
print(b)

实例052：按位或

题目：学习使用按位或 | 。

程序分析：0|0=0; 0|1=1; 1|0=1; 1|1=1

a=0o77
print(a|3)
print(a|3|7)

实例053：按位异或

题目：学习使用按位异或 ^ 。

程序分析：0^0=0; 0^1=1; 1^0=1; 1^1=0

a=0o77
print(a^3)
print(a^3^7)

实例054：位取反、位移动

题目：取一个整数a从右端开始的4〜7位。

程序分析：可以这样考虑： (1)先使a右移4位。 (2)设置一个低4位全为1,其余全为0的数。可用~(~0<<4) (3)将上面二者进行&运算。

a=int(input('输入一个数字: '))
b=0         #   0
b=~b        #   1
b=b<<4       # 10000
b=~b        # 1111
c=a>>4
d=c&b
print('a:',bin(a))
print('b:',bin(b))
print('c:',bin(c))
print('d:',bin(d))

实例055：按位取反

题目：学习使用按位取反~。

程序分析：~0=1; ~1=0;

print(~234)
print(~~234)

实例056：画圈

题目：画图，学用circle画圆形。　　　

from tkinter import *
canvas=Canvas(width=800,height=600,bg='yellow')
canvas.pack(expand=YES,fill=BOTH)
k=1
j=1
for i in range(26):
  canvas.create_oval(310-k,250-k,310+k,250+k,width=1)
  k+=jhttp://www.cppcns.com
  j+=0.3
mainloop()

实例057：画线

题目：画图，学用line画直线。

if __name__ == '__main__':
  from tkinter import *

  canvas = Canvas(width=300, height=300, bg='green') 
  canvas.pack(expand=YES, fill=BOTH)         
  x0 = 263
  y0 = 263
  y1 = 275
  x1 = 275
  for i in range(19):
    canvas.create_line(x0,y0,x0,y1, width=1, fill='red')
    x0 = x0 - 5
    y0 = y0 - 5
    x1 = x1 + 5
    y1 = y1 + 5

  x0 = 263
  y1 = 275
  y0 = 263
  for i in range(21):
    canvas.create_line(x0,y0,x0,y1,fill = 'red')
    x0 += 5
    y0 += 5
    y1 += 5

  mainloop()

实例058：画矩形

题目：画图，学用rectangle画方形。　　　

if __name__ == '__main__':
  from tkinter import *
  root = Tk()
  root.title('Canvas')
  canvas = Canvas(root,width = 400,height = 400,bg = 'yellow')
  x0 = 263
  y0 = 263
  y1 = 275
  x1 = 275
  for i in range(19):
    canvas.create_rectangle(x0,y0,x1,y1)
    x0 -= 5
    y0 -= 5
    x1 += 5
    y1 += 5

  canvas.pack()
  root.mainloop()

实例059：画图（丑）

题目：画图，综合例子。　　

if __name__ == '__main__':
  from tkinter import *
  canvas = Canvas(width = 300,height = 300,bg = 'green')
  canvas.pack(expand = YES,fill = BOTH)
  x0 = 150
  y0 = 100
  canvas.create_oval(x0 - 10,y0 - 10,x0 + 10,y0 + 10)
  canvas.create_oval(x0 - 20,y0 - 20,x0 + 20,y0 + 20)
  canvas.create_oval(x0 - 50,y0 - 50,x0 + 50,y0 + 50)
  import math
  B = 0.809
  for i in range(16):
    a = 2 * math.pi / 16 * i
    x = math.ceil(x0 + 48 * math.cos(a))
    y = math.ceil(y0 + 48 * math.sin(a) * B)
    canvas.create_line(x0,y0,x,y,fill = 'red')
  canvas.create_oval(x0 - 60,y0 - 60,x0 + 60,y0 + 60)


  for k in range(501):
    for i in range(17):
      a = (2 * math.pi / 16) * i + (2 * math.pi / 180) * k
      x = math.ceil(x0 + 48 * math.cos(a))
      y = math.ceil(y0 + 48 + math.sin(a) * B)
      canvas.create_line(x0,y0,x,y,fill = 'red')
    for j in range(51):
      a = (2 * math.pi / 16) * i + (2* math.pi / 180) * k - 1
      x = math.ceil(x0 + 48 * math.cos(a))
      y = math.ceil(y0 + 48 * math.sin(a) * B)
      canvas.crhttp://www.cppcns.comeate_line(x0,y0,x,y,fill = 'red')
  mainloop()

实例060：字符串长度

题目：计算字符串长度。　　

s='zhangguang101'
print(len(s))

例061：杨辉三角

题目：打印出杨辉三角形前十行。　　

def generate(numRows):
  r = [[1]]
  for i in range(1,numRows):
    r.append(list(map(lambda x,y:x+y, [0]+r[-1],r[-1]+[0])))
  return r[:numRows]
a=generate(10)
for i in a:
  print(i)

实例062：查找字符串

题目：查找字符串。　　

s1='aabbxuebixuebi'
s2='ab'
s3='xue'
print(s1.find(s2))
print(s1.find(s3))

实例063：画椭圆

题目：画椭圆。　

程序分析：使用 tkinter。

if __name__ == '__main__':
  from tkinter import *
  x = 360
  y = 160
  top = y - 30
  bottom = y - 30

  canvas = Canvas(width = 400,height = 600,bg = 'white')
  for i in range(20):
    canvas.create_oval(250 - top,250 - bottom,250 + top,250 + bottom)
    top -= 5
    bottom += 5
  canvas.pack()
  mainloop()

实例64：画椭圆、矩形

题目：利用ellipse 和 rectangle 画图。。　

if __name__ == '__main__':
  from tkinter import *
  canvas = Canvas(width = 400,height = 600,bg = 'white')
  left = 20
  right = 50
  top = 50
  num = 15
  for i in range(num):
    canvas.create_oval(250 - right,250 - left,250 + right,250 + left)
    canvas.create_oval(250 - 20,250 - top,250 + 20,250 + top)
    canvas.create_rectangle(20 - 2 * i,20 - 2 * i,10 * (i + 2),10 * ( i + 2))
    right += 5
    left += 5
    top += 10

  canvas.pack()
  mainloop()

实例065：画组合图形

题目：一个最优美的图案。　　

import math
from tkinter import *

class PTS:
  def __init__(self):
    self.x = 0
    self.y = 0
points = []

def LineToDemo():
  screenx = 400
  screeny = 400
  canvas = Canvas(width = screenx,height = screeny,bg = 'white')

  AspectRatio = 0.85
  MAXPTS = 15
  h = screeny
  w = screenx
  xcenter = w / 2
  ycenter = h / 2
  radius = (h - 30) / (AspectRatio * 2) - 20
  step = 360 / MAXPTS
  angle = 0.0
  for i in range(MAXPTS):
    rads = angle * math.pi / 180.0
    p = PTS()
    p.x = xcenter + int(math.cos(rads) * radius)
    p.y = ycenter - int(math.sin(rads) * radius * AspectRatio)
    angle += step
    points.append(p)
  canvas.create_oval(xcenter - radius,ycenter - radius,
           xcenter + radius,ycenter + radius)
  for i in range(MAXPTS):
    for j in range(i,MAXPTS):
      canvas.create_line(points[i].x,points[i].y,points[j].x,points[j].y)

  canvas.pack()
  mainloop()
if __name__ == '__main__':
  LineToDemo()

实例066：三数排序

题目：输入3个数a,b,c，按大小顺序输出。　　　

程序分析：同实例005。

raw=[]
for i in range(3):
  x=int(input('int%d: '%(i)))
  raw.append(x)

for i in range(len(raw)):
  for j in range(i,len(raw)):
    if raw[i]>raw[j]:
      raw[i],raw[j]=raw[j],raw[i]
print(raw)


raw2=[]
for i in range(3):
  x=int(input('int%d: '%(i)))
  raw2.append(x)
print(sorted(raw2))

实例067：交换位置

题目：输入数组，最大的与第一个元素交换，最小的与最后一个元素交换，输出数组。

li=[3,2,5,7,8,1,5]

li[-1],li[li.index(min(li))]=li[li.index(min(li))],li[-1]

m=li[0]
ind=li.index(max(li))
li[0]=li[ind]
li[ind]=m

print(li)

实例068：旋转数列

题目：有n个整数，使其前面各数顺序向后移m个位置，最后m个数变成最前面的m个数

from collections import *
li=[1,2,3,4,5,6,7,8,9]
deq=deque(li,maxlen=len(li))
print(li)
deq.rotate(int(input('rotate:')))
print(list(deq))

实例069：报数

题目：有n个人围成一圈，顺序排号。从第一个人开始报数（从1到3报数），凡报到3的人退出圈子，问最后留下的是原来第几号的那位。

if __name__ == '__main__':
  nmax = 50
  n = int(input('请输入总人数:'))
  num = []
  for i in range(n):
    num.append(i + 1)

  i = 0
  k = 0
  m = 0

  while m < n - 1:
    if num[i] != 0 : k += 1
    if k == 3:
      num[i] = 0
      k = 0
      m += 1
    i += 1
    if i == n : i = 0

  i = 0
  while num[i] == 0: i += 1
  print(num[i])

实例070：字符串长度II

题目：写一个函数，求一个字符串的长度，在main函数中输入字符串，并输出其长度。

def lenofstr(s):
  return len(s)

print(lenofstr('tanxiaofengsheng'))

实例071：输入和输出

题目：编写input()和output()函数输入，输出5个学生的数据记录。

N = 3
#stu
# num : string
# name : string
# score[4]: list
student = []
for i in range(5):
  student.append(['','',[]])

def input_stu(stu):
  for i in range(N编程客栈):
    stu[i][0] = input('input student num:\n')
    stu[i][1] = input('input student name:\n')
    for j in range(3):
      stu[i][2].append(int(input('score:\n')))

def output_stu(stu):
  for i in range(N):
    print ('%-6s%-10s' % ( stu[i][0],stu[i][1] ))
    for j in range(3):
      print ('%-8d' % stu[i][2][j])

if __name__ == '__main__':
  input_stu(student)
  print (student)
  output_stu(student)

实例072：创建链表

题目：创建一个链表。

class Node:

  def __init__(self, data):
    self.data = data
    self.next = None

  def get_data(self):
    return self.data

class List:

  def __init__(self, head):
    self.head = head

  def is_empty(self):
    return self.get_len() == 0

  def get_len(self): 
    length = 0
    temp = self.head
    while temp is not None:
      length += 1
      temp = temp.next
    return length

  def append(self, no编程客栈de):
    temp = self.head
    while temp.next is not None:
      temp = temp.next
    temp.next = nodehttp://www.cppcns.com

  def delete(self, index):
    if index < 1 or index > self.get_len():
      print("给定位置不合理")
      return
    if index == 1:
      self.head = self.head.next
      return
    temp = self.head
    cur_pos = 0
    while temp is not None:
      cur_pos += 1
      if cur_pos == index-1:
        temp.next = temp.next.next
      temp = temp.next

  def insert(self, pos, node):
    if pos < 1 or pos > self.get_len():
      print("插入结点位置不合理")
      return
    temp = self.head
    cur_pos = 0
    while temp is not Node:
      cur_pos += 1
      if cur_pos == pos-1:
        node.next = temp.next
        temp.next =node
        break
      temp = temp.next

  def reverse(self, head):
    if head is None and head.next is None:
      return head
    pre = head
    cur = head.next
    while cur is not None:
      temp = cur.next
      cur.next = pre
      pre = cur
      cur = temp
    head.next = None
    return pre

  def print_list(self, head):
    init_data = []
    while head is not None:
      init_data.append(head.get_data())
      head = head.next
    return init_data

if __name__=='__main__':
  head=Node('head')
  link=List(head)
  for i in range(10):
    node=Node(i)
    link.append(node)
  print(link.print_list(head))

实例073：反向输出链表

题目：反向输出一个链表。

class Node:

  def __init__(self, data):
    self.data = data
    self.next = None

  def get_data(self):
    return self.data

class List:

  def __init__(self, head):
    self.head = head

  def is_empty(self):
    return self.get_len() == 0

  def get_len(self): 
    length = 0
    temp = self.head
    while temp is not None:
      length += 1
      temp = temp.next
    return length

  def append(self, node):
    temp = self.head
    while temp.next is not None:
      temp = temp.next
    temp.next = node

  def delete(self, index):
    if index < 1 or index > self.get_len():
      print("给定位置不合理")
      return
    if index == 1:
      self.head = self.head.next
      return
    temp = self.head
    cur_pos = 0
    while temp is not None:
      cur_pos += 1
      if cur_pos == index-1:
        temp.next = temp.next.next
      temp = temp.next

  def insert(self, pos, node):
    if pos < 1 or pos > self.get_len():
      print("插入结点位置不合理")
      return
    temp = self.head
    cur_pos = 0
    while temp is not Node:
      cur_pos += 1
      if cur_pos == pos-1:
        node.next = temp.next
        temp.next =node
        break
      temp = temp.next

  def reverse(self, head):
    if head is None and head.next is None:
      return head
    pre = head
    cur = head.next
    while cur is not None:
      temp = cur.next
      cur.next = pre
      pre = cur
      cur = temp
    head.next = None
    return pre

  def print_list(self, head):
    init_data = []
    while head is not None:
      init_data.append(head.get_data())
      head = head.next
    return init_data

if __name__=='__main__':
  head=Node('head')
  link=List(head)
  for i in range(10):
    node=Node(i)
    link.append(node)
  print(link.print_list(head))
  print(link.print_list(link.reverse(head)))

实例074：列表排序、连接

题目：列表排序及连接。

程序分析：排序可使用sort() 方法，连接可以使用 + 号或 extend() 方法。

a=[2,6,8]
b=[7,0,4]
a.extend(b)
a.sort()
print(a)

例075：不知所云

题目：放松一下，算一道简单的题目。

if __name__ == '__main__':
  for i in range(5):
    n = 0
    if i != 1: n += 1
    if i == 3: n += 1
    if i == 4: n += 1
    if i != 4: n += 1
    if n == 3: print (64 + i)

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