在交换和分配最小和最大元素时遇到麻烦

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

def swap_min_max(arr):
    min_val, max_val = find_min_max(arr)
    if min_val is None or max_val is None:
        return arr
    
    min_index = arr.index(min_val)
    max_index = arr.index(max_val)
    
    arr[min_index], arr[max_index] = arr[max_index], arr[min_index]
    return arr

def safe_swap_min_max(arr):
    if len(arr) < 2:
        return arr  # 如果数组长度小于2，不需要交换
    
    return swap_min_max(arr)

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

def swap_min_max(arr):
    min_val, max_val = find_min_max(arr)
    if min_val is None or max_val == min_val:
        return arr
    
    min_index = arr.index(min_val)
    max_index = arr.index(max_val)
    
    arr[min_index], arr[max_index] = arr[max_index], arr[min_index]
    return arr

def safe_swap_min_max(arr):
    if len(arr) < 2:
        return arr  # 如果数组长度小于2，不需要交换
    
    return swap_min_max(arr)

# 示例使用
arr = [3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5]
print("原始数组:", arr)
print("交换后的数组:", safe_swap_min_max(arr))