(...不要问这些数组的值,它们是拉丁美洲的食品品牌,与一些朋友开了个玩笑)。
def binSearch(arr, i, lower=0, upper=None):
if upper is None:
upper = len(arr)+1
idx = (lower+upper)//2
if arr[idx] == i:
print(idx, arr[idx],'\n')
#return idx
elif arr[idx] != i and upper-lower<2:
print("Not found \n")
#return False
elif arr[idx] < i:
print(idx, arr[idx])
binSearch(arr, i, idx, upper)
elif arr[idx] > i:
print(idx, arr[idx])
binSearch(arr, i, lower, idx)
myArray = ["Chabona", "F-Nandito VII", "La Bichy", "Manaos", "Martín y Enzo", "Pitusas", "Trompis", "Ugi's", "VAMOS MANAOS", "Villamanaos"]
binSearch(myArray, "Manaos")
binSearch(myArray, "Coca-Cola")
该程序完全按照我的预期做–它输出以下内容:
5 Pitusas
2 La Bichy
3 Manaos
5 Pitusas
2 La Bichy
1 F-Nandito VII
Not found
然而,这是我所得到的,当我注释掉所有打印语句使其返回idx
或None
代替,然后用更换电话print(binSearch(myArray, "Manaos"))
和print(binSearch(myArray, "Coca-Cola"))
:
None
None
它显然应该返回3
,False
但是什么也不会返回。我究竟做错了什么?
您不返回:
return binSearch(arr, i, lower, idx)
您还需要根据情况返回:
def binSearch(arr, i, lower=0, upper=None):
if upper is None:
upper = len(arr)+1
idx = (lower+upper)//2
if arr[idx] == i:
print(idx, arr[idx],'\n')
return idx # return 3/idx
elif arr[idx] != i and upper-lower<2:
print("Not found \n")
return False # return False
elif arr[idx] < i:
print(idx, arr[idx])
return binSearch(arr, i, idx, upper)
elif arr[idx] > i:
print(idx, arr[idx])
return binSearch(arr, i, lower, idx)
print(binSearch(myArray, "Manaos"))
print(binSearch(myArray, "Coca-Cola"))
5 Pitusas
2 La Bichy
3 Manaos
3
5 Pitusas
2 La Bichy
1 F-Nandito VII
Not found
False
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