这个“数组中的最大-最小元素”逻辑有什么问题？

def find_max_min(arr):
    if not arr:
        return None, None
    
    max_val = min_val = arr[0]
    
    for num in arr:
        if num > max_val:
            max_val = num
        if num < min_val:
            min_val = num
    
    return max_val, min_val

def find_max_min(arr):
    if not arr:
        return None, None
    # 其余代码同上

def find_max_min_divide_conquer(arr, low, high):
    if low == high:
        return arr[low], arr[low]
    
    if high - low == 1:
        return (arr[low], arr[high]) if arr[low] < arr[high] else (arr[high], arr[low])
    
    mid = (low + high) // 2
    min1, max1 = find_max_min_divide_conquer(arr, low, mid)
    min2, max2 = find_max_min_divide_conquer(arr, mid + 1, high)
    
    return min(min1, min2), max(max1, max2)