在洛谷使用c#刷题如何提高输入输出效率

2024年7月9日

可以适当提高StreamReader的bufferSize会有一点小提升

这是我目前使用的方案，有什么更优的方案欢迎大家分享

使用StreamReader和StreamWriter进行输入和输出+自己解析字符串，例如P1253

public class P1253
{
    public static void Main()
    {
        using (StreamReader sr = new StreamReader(Console.OpenStandardInput()))
        {
            using (StreamWriter sw = new StreamWriter(Console.OpenStandardOutput()))
            {
                sw.AutoFlush = false;  // 禁用自动刷新以提高性能
                int n = ReadInt(sr);
                int m = ReadInt(sr);
                var nums = new int[n];
                for (int i = 0; i < n; i++)
                {
                    nums[i] = ReadInt(sr);
                }
                SegmentTreeSetAndAdd segmentTree = new SegmentTreeSetAndAdd(n);
                segmentTree.Build(nums);
                for (int i = 0; i < m; i++)
                {
                    int op = ReadInt(sr);
                    if (op == 1)
                    {
                        segmentTree.SetRangeValue(ReadInt(sr), ReadInt(sr), ReadInt(sr));
                    }
                    else if (op == 2)
                    {
                        segmentTree.AddRangeValue(ReadInt(sr), ReadInt(sr), ReadInt(sr));
                    }
                    else
                    {
                        var max = segmentTree.QueryMax(ReadInt(sr), ReadInt(sr));
                        sw.WriteLine(max);
                    }
                }
                sw.Flush();  // 最后手动刷新缓冲区
            }
        }    
    }
    public static int ReadInt(StreamReader reader)
    {
        int ans = 0;
        int read = reader.Read();
        bool sign = false;
        while (read > '9' || read < '0')
        {
            if (read == '-')
                sign = true;
            read = reader.Read();
        }
        while (read <= '9' && read >= '0')
        {
            ans = ans * 10 + read - '0';
            read = reader.Read();
        }
        if (sign)
            ans = -ans;
        return ans;
    }

}

这是老的使用Console.ReadLine+Split的实现

    public static void Main()
    {
        var headInput = Console.ReadLine().Trim();
        var headSpit = headInput.Split(' ');
        int n = int.Parse(headSpit[0]);
        int m = int.Parse(headSpit[1]);
        var arrayInput = Console.ReadLine().Trim();
        var arraySpit = arrayInput.Split(' ');
        var nums = new int[n];
        for (int i = 0; i < arraySpit.Length; i++)
        {
            nums[i] = int.Parse(arraySpit[i]);
        }
        SegmentTreeSetAndAdd segmentTree = new SegmentTreeSetAndAdd(n);
        segmentTree.Build(nums);
        for (int i = 0; i < m; i++)
        {
            var methodInput = Console.ReadLine().Trim();
            var methodSpit = methodInput.Split(' ');
            int op = int.Parse(methodSpit[0]);
            if (op == 1)
            {
                segmentTree.SetRangeValue(int.Parse(methodSpit[1]), int.Parse(methodSpit[2]), int.Parse(methodSpit[3]));
            }
            else if (op == 2)
            {
                segmentTree.AddRangeValue(int.Parse(methodSpit[1]), int.Parse(methodSpit[2]), int.Parse(methodSpit[3]));
            }
            else
            {
                var max = segmentTree.QueryMax(int.Parse(methodSpit[1]), int.Parse(methodSpit[2]));
                Console.WriteLine(max);
            }
        }
    }

效率对比

Console.ReadLine+Split

StreamReader+StreamWriter