力扣704.二分查找

def search(nums, target):
    start, end = 0, len(nums)-1
    while start < end:
        mid = start + (end - start)//2
        if target == nums[mid]:
            return mid
        if target < nums[mid]:
            end = mid - 1
        else:
            start = mid + 1
    return -1

nums = [-1, 0, 3, 5, 9, 12]
target = 9
print(search(nums, target))
# 输出4

def search(nums, target):
    def bs(i, j):
        if i > j:
            return -1  # 设置终止条件
        m = (i + j) // 2
        if target == nums[m]:
            return m
        elif target < nums[m]:
            return bs(i, m - 1)
        else:
            return bs(m + 1, j)

    return bs(0, len(nums) - 1)