基础
读程序，总结程序的功能:
numbers=1
for i in range(0,20):
numbers*=2
print(numbers)
#计算2的20次方
summation=0
num=1
while num<=100:
if (num%3==0 or num%7==0) and num%21!=0:
summation += 1
num+=1
print(summation)
#统计100以内能被3或者7整除并且不能被两者同时整除的数的个数
编程实现(for和while各写⼀遍):
- 求1到100之间所有数的和、平均值
def sum_avg():
sum = 0
count = 0
for num in range(1,101):
sum += num
count += 1
return '所有数的和是%d,平均值是%.1f'%(sum,sum/count)
# print(sum_avg())
- 计算1-100之间能3整除的数的和
def sum_three():
sum = 0
for num in range(1,101):
if not num % 3:
sum += num
return '1-100之间能被3整除的数的和是%d'%sum
# print(sum_three())
- 计算1-100之间不能被7整除的数的和
def sum_seven():
sum = 0
for num in range(1,101):
if num % 7:
sum += num
return '1-100之间能被3整除的数的和是%d'%sum
# print(sum_seven())
稍微困难
- 求斐波那契数列中第n个数的值：1，1，2，3，5，8，13，21，34....
def num(count):
sum1 = 1
sum2 = 1
for num in range(1,count):
if count == 1:
return sum1
elif count == 2:
return sum2
elif num & 1 == 1:
sum1 += sum2
elif num & 1 == 0:
sum2 += sum1
if count & 1 == 1:
return sum1
else:
return sum2
# print(num(7))
#用递归做：
def fun(num):
if num == 1:
return 1
if num == 2:
return 1
return fun(num-1)+ fun(num-2)
#优化
def fun(n):
pre_1 = 0
pre_2 = 1
current = 0
for _ in range(n):
current = pre_1 + pre_2
pre_2 = pre_1
pre_1 = current
return current
- 判断101-200之间有多少个素数，并输出所有素数。判断素数的⽅法：⽤⼀个数分别除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
import math
def prime():
count = 0
for i in range(101,201):
j = 2
while j <= math.sqrt(i):
if i % j == 0:
break
j += 1
else:
count += 1
return count
# print(prime())
- 打印出所有的⽔仙花数,所谓⽔仙花数是指⼀个三位数，其各位数字⽴⽅和等于该数本身。例如：153是
⼀个⽔仙花数,因为153 = 1^3 + 5^3 + 3^3
def print_flower():
for i in range(100,1000):
if (i % 10)**3 + (i // 100)**3 + (i // 10 % 10)**3 == i:
print('%d是水仙花数'%i)
# print(print_flower())
- 有⼀分数序列：2/1,3/2,5/3,8/5,13/8,21/13...求出这个数列的第20个分数
分⼦：上⼀个分数的分⼦加分⺟ 分⺟: 上⼀个分数的分⼦ fz = 2 fm = 1 fz+fm / fz
def fenzi(num):
fenzi = 2
fenmu = 1
center = 0
if num == 1:
return '%d/%d'%(fenzi,fenmu)
for i in range(1,num):
center = fenzi
fenzi += fenmu
fenmu = center
return '%d/%d'%(fenzi,fenmu)
# print(fenzi(20))
- 给⼀个正整数，要求：1、求它是⼏位数 2.逆序打印出各位数字
def decide(num):
count = 0
while True:
print(num%10) #打印末尾数
num = num // 10
count += 1
if num == 0:
print(count) # 打印位数
break
# decide(1234)
