剑指Offer(Python多种思路实现):1~n整数中1出现的次数
面试43题:
题目:1~n整数中1出现的次数
题:输入一个整数n,求1~n这n个整数的十进制表示中1出现的次数。例如,输入12,1~12这些整数中包含1的数字有1,10,11,12一共出现了5次。
解题思路一:直接累加1~n中每个整数中1出现的次数。
class Solution:
def NumberOf1Between1AndN_Solution(self, n):
# write code here
totalCount=0
for i in range(1,n+1):
totalCount+=self.NumberOf1Core(i)
return totalCount
def NumberOf1Core(self,number):
count=0
while(number):
if number%10==1:
count+=1
number=number//10
return count
解题思路二:
class Solution:
def NumberOf1Between1AndN_Solution(self, n):
# write code here
count=0
for i in range(1,n+1):
for j in str(i):
if j=="1":
count+=1
return count