<每日一题>题目6:二分查找

 #二分查找
 '''
 1.end问题
 2.44对应的end<start 找不到情况
 3.返回值递归的情况
 4,611,aim太大的情况
 '''
 l = [2,3,5,10,15,16,18,22,26,30,32,35,41,42,43,55,56,66,67,69,72,76,82,83,88]
 def find(l,aim,start=0,end=None):
     end = len(l) if end is None else end
     Mid_index = (end - start) // 2 +start
     if aim <= l[len(l)-1]:
         if end >= start:
             if l[Mid_index] > aim:
                 return find(l,aim,start=start,end = Mid_index-1)
             elif l[Mid_index] < aim:
                 return find(l,aim,start=Mid_index+1,end=end)
             elif l[Mid_index] == aim:
                 return Mid_index
         else:
             return '找不到!'
     else:
         return '比列表最大数都大,找不到!'
 l = [2,3,5,10,15,16,18,22,26,30,32,35,41,42,43,55,56,66,67,69,72,76,82,83,88]
 ret = find(l,411)
 ret1 = find(l,44)
 ret2 = find(l,66)
 ret3 = find(l,67)
 print(ret,ret1,ret2,ret3)

　　运行结果:

 比列表最大数都大,找不到! 找不到! 17 18