用于解答算法题目的Python3代码框架

前言

最近在实习，任务并不是很重，就利用闲暇时间使用Python3在PAT网站上刷题，并致力于使用Python3的特性和函数式编程的理念，其中大部分题目都有着类似的输入输出格式，例如一行读入若干个数字，字符串，每行输出多少个字符串等等，所以产生了很多重复的代码。

Python代码

于是我就利用VS Code的代码片段功能编写了一个用于处理这些输入输出的代码框架，并加入了测试功能（写函数前先写测试时正确的事情）。代码如下

"""Simple Console Program With Data Input And Output."""
import sys
import io


def read_int():
    """Read a seris of numbers."""
    return list(map(int, sys.stdin.readline().split()))


def test_read_int():
    """Test the read_int function"""
    test_file = io.StringIO("1 2 3\n")
    sys.stdin = test_file
    assert read_int() == [1, 2, 3], "read_int error"


def read_float():
    """Read a seris of float numbers."""
    return list(map(float, sys.stdin.readline().split()))


def test_read_float():
    """Test the read_float function"""
    test_file = io.StringIO("1 2 3\n")
    sys.stdin = test_file
    assert read_float() == [1.0, 2.0, 3.0], "read_float error"


def read_word():
    """Read a seris of string."""
    return list(map(str, sys.stdin.readline().split()))


def test_read_word():
    """Test the read_word function"""
    test_file = io.StringIO("1 2 3\n")
    sys.stdin = test_file
    assert read_word() == ["1", "2", "3"], "read_word error"


def combine_with(seq, sep=' ', num=None):
    """Combine list enum with a character and return the string object"""
    res = sep.join(list(map(str, seq)))
    if num is not None:
        res = str(seq[0])
        for element in range(1, len(seq)):
            res += sep + \
                str(seq[element]) if element % num != 0 else '\n' + \
                str(seq[element])
    return res


def test_combile_with():
    """Test the combile_with function."""
    assert combine_with([1, 2, 3, 4, 5], '*', 2) == """1*2 3*4 5""", "combine_with error."


def main():
    """The main function."""
    pass


if __name__ == '__main__':
    sys.exit(int(main() or 0))

VS Code代码片段

添加到VS Code的默认代码片段的操作大致如下：

• 文件->首选项->用户代码片段，选择Python

• 编辑"python.json"文件如以下内容

  {
  /*
     // Place your snippets for Python here. Each snippet is defined under a snippet name and has a prefix, body and 
     // description. The prefix is what is used to trigger the snippet and the body will be expanded and inserted. Possible variables are:
     // $1, $2 for tab stops, ${id} and ${id:label} and ${1:label} for variables. Variables with the same id are connected.
     // Example:
     "Print to console": {
        "prefix": "log",
        "body": [
            "console.log('$1');",
            "$2"
        ],
        "description": "Log output to console"
    }
  */
  "Simple Console Program With Data Input And Output": {
        "prefix": "simple",
        "body": ["\"\"\"Simple Console Program With Data Input And Output.\"\"\"\nimport sys\n\ndef read_int():\n \"\"\"Read a seris of numbers.\"\"\"\n return list(map(int, sys.stdin.readline().split()))\n\n\ndef read_float():\n \"\"\"Read a seris of float numbers.\"\"\"\n return list(map(float, sys.stdin.readline().split()))\n\n\ndef read_word():\n \"\"\"Read a seris of string.\"\"\"\n return list(map(str, sys.stdin.readline().split()))\n\n\ndef combine_with(seq, sep=' ', num=None):\n \"\"\"Combine list enum with a character and return the string object\"\"\"\n res = sep.join(list(map(str, seq)))\n if num is not None:\n res = str(seq[0])\n for element in range(1, len(seq)):\n res += sep + str(seq[element]) if element % num != 0 else '\\n' + str(seq[element])\n return res\n\n\ndef main():\n \"\"\"The main function.\"\"\"\n pass\n\n\nif __name__ == '__main__':\n sys.exit(int(main() or 0))\n"
        ],
        "description": "Simple Console Program With Data Input And Output"
    }
  }
  

  然后再编写Python代码的时候，键入"simple"就可以自动输入以上模板。

总结

虽然Python不是特别适合解答算法题目这种性能要求很高的场景，但是在一些模拟题目如各种排队型和字符串处理的条件下，使用Python可以极大地提高解体效率，另外还可以使用cimport使用C语言的数据结构和Python的语法特性，效率不弱于原生C代码。