1、math的一些常用函数
print(round(2.5)) #round()是四舍六入,五取偶;不是math下面的函数 print(round(1.2)) import math print(math.floor(2.5)) #向下取整 print(math.ceil(2.5)) #向上取整 print(math.sqrt(3)) #开平方 print(math.pi) #pai print(math.e) #自然常数
2、杨辉三角
lst=[] n=6 for i in range(n): row=[1] lst.append(row) if i==0: continue for j in range(i-1): row.append(lst[i-1][j]+lst[i-1][j+1]) else: row.append(1) print(lst)
3、求10万以内的质数方法时间效率的比较
import math n=100000 p=[] count=0 flag=True start=datetime.datetime.now() for x in range(2,n): for i in p: count+=1 if x%i==0: flag=False break if i>=math.ceil(x**0.5): flag=True break if flag: p.append(x) delta=(datetime.datetime.now()-start).total_seconds() print(len(p)) print(count) print(delta)
结果:
9592 754026 0.447888
import math import datetime n=100000 p=[] count=0 start=datetime.datetime.now() for x in range(2,n): for i in p: count+=1 if(x%i)==0: break else: p.append(x) delta=(datetime.datetime.now()-start).total_seconds() print(len(p)) print(count) print(delta)
结果:
9592 46314476 9.33169