Python 算法（一）——二分查找

numbers=[1,3,5,7,8,13,14,15,17,18,24,30,43,56]
head,tail=0,len(numbers)
search=int(input("Enter a number to search"))

while tail-head>1:
    mid=(head+tail)//2
    if search<numbers[mid]:
        tail=mid
    if search>numbers[mid]:
        head=mid+1
    if search==numbers[mid]:
        ans=mid
        break
    
else:
    if search==numbers[head]:
        ans=head
    else:
        ans=-1
print(ans)