python基础知识之递归函数 经典函数实例

二分查找法

l=[1,2,3,4,44,46,47,48,49,50,55,54,57,58,89,90,98]

def  star(l,aim,st=0,end=None):
    end=len(l) if end is None else end
    xde=(end - st)//2+st
    ai=l[xde]
    if aim in l:
      if ai<aim:
        return  star(l,aim,st=xde+1,end=end)
      elif ai>aim:
        return star(l,aim,st=st,end=xde-1)
      else:
        return xde
    else:
        return("不在")
ret=star(l,44)
print(ret)

斐波那契 1,1,2,3,5,8
def  fib(n,l=[]):
    l[0]+=1
    if n==1 or n==2:
        l[0] -= 1
        return 1, 1
    else:
        a,b=fib(n-1)
        l[0] -= 1
        if l[0]==0:
            return a+b
        return b,a+b
ret=fib(3)
print(ret)

阶乘  3！3*2*1
def jie(n):
    if n==1:
        return 1
    return n*jie(n-1)
print(jie(1))