100个Python小例子(练习题三)
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+=j
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.create_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):
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, 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))
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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