Question

在我的二进制搜索中，如果找不到目标，我想返回下一个最高元素的索引。

E.g [1,2,3,4,5,7]如果我要搜索6，则应返回7的位置。

我正在测试 aList = [2, 8, 17, 42, 79, 85]

当我搜索3，18或80时，它会有效。但是，它会返回比搜索9，43或86时应该低1的索引。

def recursiveBinarySearch(aList, first, last, target):

    if last - first + 1 <= 0:
        return False
    else:
        midpoint = first + (last - first) // 2
        if aList[midpoint] == target:
            return midpoint
        elif last - first + 1 == 1:
            return midpoint 
        else:
            if target < aList[midpoint]:
                return recursiveBinarySearch(aList, first, midpoint-1, target)
            else:
                return recursiveBinarySearch(aList, midpoint+1, last, target)

Answer 1

aList = [1,3,5,6,8,9,10,12,34,56,78,456, 777]
def recursiveBinarySearch(aList, target, index):
    #aList = sorted(aList)
    print(aList, index)
    if len(aList) <= 1:
        if index==0 and aList[0]==target:
            return index
        else:   
            return index+1

    else:
        midpoint = len(aList) // 2
#        print(midpoint)
        if aList[midpoint] == target:
            return aList.index(target)+index
        else:
            if target < aList[midpoint]:
                return recursiveBinarySearch(aList[:midpoint],target, index)
            else:
                return recursiveBinarySearch(aList[midpoint:],target, index+len(aList[:midpoint]))

print(recursiveBinarySearch(aList,3,0))

这应该工作:) 修复了搜索第一个数字时的错误。

使用二分搜索返回下一个最高值

1 个答案: