python实现二分查找

python实现二分查找的两种方法

#   二分查找

def search_1(arr, target):
    left = 0
    right = len(arr) - 1
    while left <= right:
        mid = (left + right) // 2
        if arr[mid] == target:
            return mid, arr[mid]
        elif arr[mid] < target:
            left = mid + 1
        else:
            right = mid - 1
    else:
        return -1

arr = [2, 4, 6, 8, 10, 12, 14, 16]
target = 16
# res = search_1(arr, target)
# print(res)

def search_2(arr, target, left, right):
    if left <= right:
        mid = (left + right) // 2
        if arr[mid] == target:
            return mid, arr[mid]
        elif arr[mid] < target:
            return search_2(arr, target, mid + 1, right)
        else:
            return search_2(arr, target, left, mid - 1)
    else:
        return -1


arr = [2, 4, 6, 8, 10, 12, 14, 16]
target = 12
result = search_2(arr, target, 0, len(arr)-2)
print(result)