"""
二分查找算法python实例
--------------------------------------
在python里，最简单的实现方法是下面这句，亦可在字符串里查找子字符串
if num in tuple:
print 'ok'
--------------------------------------
下面的代码是单纯从算法角度考虑
"""
# -*- coding: utf-8 -*-
class Dichotomy():
def __init__(this, thetuple):
this.thetuple = thetuple
this.begin = 0
this.end = len(thetuple) - 1
this.middle = 0
def find(this, num):
this.middle = (this.begin + this.end) / 2
if num < this.thetuple[this.middle]:
this.end = this.middle - 1
elif num > this.thetuple[this.middle]:
this.begin = this.middle + 1
else:
return [this.middle, num]
if this.begin > this.end:
return None
return this.find(num)
def example(thetuple, num):
dichotomy = Dichotomy(thetuple)
result = dichotomy.find(num)
if result is None:
print 'not found.'
else:
print result[1], 'is matched at', result[0]
if __name__ == '__main__':
example([2, 7, 8, 15, 30, 56, 68, 99], 8)
#end