列表查找的两种方法

def linear_search(data_set, value):
    for i in range(len(data_set)):
        if value == data_set[i]:
            return i
    return 

def binary_search(data_set, low, high, val):
    
    while low <= high:
        mid = (low + high) // 2
        if data_set[mid] == val:
            return mid
        elif val > data_set[mid]:   # 值在列表右边
            low = mid + 1
        else:       # 值在列表左边
            high = mid -1
    return 

def binary_search2(data_set, low, high, val):
    if low <= high:
        mid = (low+high) // 2
        if data_set[mid] == val:
            return mid
        elif val < data_set[mid]:
            binary_search2(data_set, low, mid-1, val)
        else:
            binary_search2(data_set, mid+1, high, val)
    else:
        return