功能说明
统计指定范围[0, n]内所有的奇数数字中，3的数量总和。
实现代码
#!/usr/bin/python
def calcCountOfDigit3InBase(base):
if base == 10: return 1
return 10 * calcCountOfDigit3InBase(base / 10) + (base / 20)
def calcCountOfDigit3(n):
base = 10
while n / base > 0:
base *= 10
base /= 10
count = 0
while base >= 10:
m = n / base
count += m * calcCountOfDigit3InBase(base)
if m > 3:
count += base / 2
if m == 3:
count += ((n + 1) % base) / 2
n = n % base
base /= 10
if n >= 3:
count += 1
return count
def printCountOfDigit3(n):
print("%s = %s" % (n, calcCountOfDigit3(n)))
输出结果
printCountOfDigit3(800000000)
printCountOfDigit3( 60000000)
printCountOfDigit3( 6000000)
printCountOfDigit3( 200000)
printCountOfDigit3( 70000)
printCountOfDigit3( 8000)
printCountOfDigit3( 100)
printCountOfDigit3( 70)
printCountOfDigit3( 1)
printCountOfDigit3(866278171)
seewin@seewin:~$ python StatsCountOfDigit3.py
800000000 = 410000000
60000000 = 29000000
6000000 = 2600000
200000 = 60000
70000 = 22500
8000 = 2100
100 = 15
70 = 12
1 = 0
866278171 = 441684627
不知结论正确与否，欢迎批评指正。
