Python -查找第二小数

def find_second_smallest_sort(nums):
    if len(nums) < 2:
        return None
    sorted_nums = sorted(set(nums))
    return sorted_nums[1] if len(sorted_nums) > 1 else None

# 示例
nums = [4, 2, 1, 5, 3]
print(find_second_smallest_sort(nums))  # 输出: 2

def find_second_smallest_one_pass(nums):
    if len(nums) < 2:
        return None
    first_min = second_min = float('inf')
    for num in nums:
        if num < first_min:
            second_min = first_min
            first_min = num
        elif first_min < num < second_min:
            second_min = num
    return second_min if second_min != float('inf') else None

# 示例
nums = [4, 2, 1, 5, 3]
print(find_second_smallest_one_pass(nums))  # 输出: 2