三分查找算法设计思路和二分查找算法类似,将区间三等分,确定5种条件判断,最后用递归求解就行,完整代码如下
#三分查找
def ThreeSearch(List,k,left,right):
if left>=right:
return False
#确定将区间三等分的2个点
mid1=(right-left)//3+left
mid2=(right-left)*2//3+left
#分5种情况讨论,包括3个区间,2个点
if List[mid1]==k:
return mid1
elif List[mid2]==k:
return mid2
elif List[mid1]>k:
return ThreeSearch(List,k,left=left,right=mid1)
elif k>List[mid1] and k<List[mid2]:
return ThreeSearch(List,k,left=mid1+1,right=mid2)
else:
return ThreeSearch(List,k,left=mid2+1,right=right)
if __name__=='__main__':
List = [i for i in range(1, 100, 2)]
print(ThreeSearch(List, 97, 0, len(List)))