[Algorithm] 이진 탐색

재귀함수 사용

def binary_search(array, target, start, end):
    if start > end:
        return None
    mid = (start + end) // 2

    if array[mid] == target:
        return mid
    elif array[mid] > target:
        return binary_search(array, target, start, mid - 1)
    else:
        return binary_search(array, target, mid + 1, end)

n, target = list(map(int, input().split()))

array = list(map(int, input().split()))

result = binary_search(array, target, 0, n-1)
if result == None:
    print("원소x")
else:
    print(result + 1)

 

 

 

반복문 사용

def binary_search(array, target, start, end):
    while start <= end:
        mid = (start + end) // 2

        if array[mid] == target:
            return mid
        elif array[mid] > target:
            end = mid - 1
        else:
            start = mid + 1
    return None

n, target = list(map(int, input().split()))

array = list(map(int, input().split()))

result = binary_search(array, target, 0, n-1)
if result == None:
    print("원소x")
else:
    print(result + 1)