Python 练习实例12
题目:判断101-200之间有多少个素数,并输出所有素数。
程序分析:判断素数的方法:用一个数分别去除2到sqrt(这个数),如果能被整除,则表明此数不是素数,反之是素数。
程序源代码:
实例(Python 2.0+)
#!/usr/bin/python
# -*- coding: UTF-8 -*-
h = 0
leap = 1
from math import sqrt
from sys import stdout
for m in range(101,201):
k = int(sqrt(m + 1))
for i in range(2,k + 1):
if m % i == 0:
leap = 0
break
if leap == 1:
print ('%-4d' % m)
h += 1
if h % 10 == 0:
print ('')
leap = 1
print ('The total is %d' % h)
以上实例输出结果为:
101 103 107 109 113 127 131 137 139 149 151 157 163 167 173 179 181 191 193 197 199 The total is 21
Python 100例
至尊宝
521***41@qq.com
使用集合解法:
#!/usr/bin/python # -*- coding: UTF-8 -*- l = [] for i in range(101,200): for j in range(2,i-1): if i%j ==0: break else: l.append(i) print(l) print("总数为:%d" % len(l))至尊宝
521***41@qq.com
Eric
382***115@qq.com
参考解法:
#!/usr/bin/python # -*- coding: UTF-8 -*-# from math import sqrt count=0 pn=1 for i in range(101,201): k=int(sqrt(i)) for j in range(2,k+1): if i%j==0: pn=0 break if pn==1: count+=1 print i pn=1 print "total number is %d"%countEric
382***115@qq.com
swordzjc
hfu***9@163.com
Python3 测试实例:
#!/usr/bin/python3 list1 = [] list2 = [] for x in range(2, 101): for i in range(2, x+1): sum = x * i if (sum < 200) & (sum > 101): list1.append(sum) for m in range(101, 200): list2.append(m) list3 = list(set(list2) ^ set(list1)) print(list1, '\n') print(list3) print("总数为:", len(list3))swordzjc
hfu***9@163.com
奈琉
115***4268@qq.com
判断素数的方式我选用了排除法,采用切片复制原有列表,逐一排除非素数,则剩余的列表中元素皆为素数。
#!/usr/bin/python # -*- coding: UTF-8 -*- import math m=range(101,201) p=m[:] for i in range(101,201): for j in range(2,int(math.sqrt(i)+1)): if i % j == 0: p.remove(i) break print(p) print("101至200之间的素数一共有%d个"%len(p))奈琉
115***4268@qq.com
大愚
923***317@qq.com
参考方法:
#!/usr/bin/python # -*- coding: UTF-8 -*- import math def sushu(): result = [] for i in range(101,201): flag = True for j in range(2,int(math.sqrt(i))+1): if i % j == 0: flag = False continue if flag == True: result.append(i) print result sushu()大愚
923***317@qq.com
Kunz
sun***gup@163.com
参考方法:
#!/usr/bin/python # -*- coding: UTF-8 -*- from math import sqrt l=[] for x in range(101,201): l.append(x) for i in range(2,int(sqrt(x))+1): if x%i==0: l.pop() break n=len(l) print l print '总数为:',nKunz
sun***gup@163.com
Think-dfrent
iwa***aoiy@live.com
python3 测试实例:去除除2以外的偶数 提高效率
#!/usr/bin/env python3 import math def sushu(start,end): count=0 for i in range(start,end+1): if(i%2==0 and i!=2): #去除除2以外的偶数 continue for j in range(2,int(math.sqrt(i))+1): if(i%j==0): break else: count=count+1 print(i,end=" ") print("") print("count",count) return #start=int(input("start:\n")) #end=int(input("end:\n")) #sushu(start,end) sushu(101,200)Think-dfrent
iwa***aoiy@live.com
AnnieHe
380***802@qq.com
参考方法:
# -*- coding: UTF-8 -*- def a(n): L = [] for i in range(2,n-1): L.append(n%i) if 0 not in L: return True print filter(a,range(101,200))AnnieHe
380***802@qq.com
周周
zhi***zhou@hotmail.com
Python3 测试:
检查 y 能否被 2 到 y**0.5 之间的整数整除,如果能则 break,如果不能,将该数加入列表并 break。
#!/usr/bin/python3 def prim(m, n): arr = [] for x in range(m, n + 1): for y in range(2, int(x ** 0.5)): if (x / y) == int(x / y): break else: arr.append(x) break return arr print(prim(101, 200))周周
zhi***zhou@hotmail.com
Echo
csz***13@163.com
我写了两种方法,一种是迭代器:
#!/usr/bin/python # -*- coding: UTF-8 -*- def prime(): n = 2 while 1: for i in range(2, n+1): if n%i: continue else: if i==n : yield n else: break n+=1 L = [] for i in prime(): if 101<=i<=200: L.append(i) if i>=200: break print('一共有{}个素数,这些素数分别是:{}'.format(len(L),L))运行结果:
另一种是生成器一行搞定:
#!/usr/bin/python # -*- coding: UTF-8 -*- L = list(filter(lambda x: x not in set([i for i in range(101,201) for j in range(2,i) if not i%j]), range(101,201))) print('一共有{}个素数,这些素数分别是:{}'.format(len(L),L))Echo
csz***13@163.com