100 个 Python 小例子(练习题三)
作者:野客
前期练习:
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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