leetcode_204. Count Primes 统计素数
2016-11-07 22:08
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题目:
Description:
Count the number of prime numbers less than a non-negative number, n.
题意:
给定数字n,统计小于n的数中所有素数的个数
代码:
class Solution(object):
global Primes
Primes = []
def isPrimes(self, x) :
if x < 2 :
return False
if x == 2 :
return True
if x%2 == 0 :
return False
sql = int(x**0.5)
global Primes
len_P = len(Primes)
for i in range(len_P) :
if Primes[i] > (sql+1) :
break
if x%(Primes[i]) == 0 :
return False
return True
def countPrimes(self, n):
"""
:type n: int
:rtype: int
"""
res = 0
global Primes
Primes = []
for x in range(n) :
if self.isPrimes(x) == True :
res += 1
Primes.append(x)
return res
笔记:
这是一道用python写AC不了的题。表示各种思想用python实现,都TLE。
最后还是看了大神的cpp代码才过的:http://blog.csdn.net/sunao2002002/article/details/45583723
Description:
Count the number of prime numbers less than a non-negative number, n.
题意:
给定数字n,统计小于n的数中所有素数的个数
代码:
class Solution(object):
global Primes
Primes = []
def isPrimes(self, x) :
if x < 2 :
return False
if x == 2 :
return True
if x%2 == 0 :
return False
sql = int(x**0.5)
global Primes
len_P = len(Primes)
for i in range(len_P) :
if Primes[i] > (sql+1) :
break
if x%(Primes[i]) == 0 :
return False
return True
def countPrimes(self, n):
"""
:type n: int
:rtype: int
"""
res = 0
global Primes
Primes = []
for x in range(n) :
if self.isPrimes(x) == True :
res += 1
Primes.append(x)
return res
笔记:
这是一道用python写AC不了的题。表示各种思想用python实现,都TLE。
最后还是看了大神的cpp代码才过的:http://blog.csdn.net/sunao2002002/article/details/45583723
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