校ACM第三次次预选赛 - 总结

总结

第三次预选赛面向的是专科的同学, 题目难度相对上两场会容易的多, 但是也有比较难的题目. 比赛共274人参加, 共3362次提交, 595次AC

-----------------------下面是题解----------------------------------------

A 伟大的征途

//直接输出并换行即可, 记得换行!!

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
                Console.WriteLine("Hello World!");
            }
        }
    }
}

B 闰年

//输入一个年份, 判断是不是闰年即可

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
 
namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            int year;
            year=int.Parse(Console.ReadLine());
            if(year%4==0&&year%100!=0||year%400==0)
                Console.WriteLine("leap year");
                else
                    Console.WriteLine("not leap year");
        }
    }
}

C 帮帮老师1

只涉及基本的选择判断, 按照题意选择即可

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
 
namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            int score;
            score=int.Parse(Console.ReadLine());
            if(score>=0&&score<=100)
            {
                switch(score/10)
                {
                    case 10 :
                    case 9: Console.WriteLine("A");break;
                    case 8: Console.WriteLine("B"); break;
                    case 7: Console.WriteLine("C"); break;
                    case 6: Console.WriteLine("D"); break;
                    default:Console.WriteLine("E");break;
                }
            }
        }
    }
}

帮帮老师2

只涉及基本的选择判断和循环输入, 然后求平均数即可

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            int n, m;
            string str = Console.ReadLine();
            string[] str_nm = str.Split(' ');
            n = int.Parse(str_nm[0]);
            m = int.Parse(str_nm[1]);
            string Read_n = Console.ReadLine();
            string Read_m = Console.ReadLine();
            float k,avg_n=0,avg_m=0;
            string[] str_n = new string[n];
            str_n = Read_n.Split(' ');
            string[] str_m = Read_m.Split(' ');
            float[] arr_n = new float[str_n.Length];
            for (int i = 0; i < str_n.Length; i++)
            {
                k = float.Parse(str_n[i]);
                if(k>=0&&k<=100)
                    arr_n[i] = k;
            }
            float[] arr_m = new float[str_m.Length];
            for (int i = 0; i < str_m.Length; i++)
            {
                k = float.Parse(str_m[i]);
                if (k >= 0 && k <= 100)
                    arr_m[i] = k;
            }
            for (int i = 0; i < n; i++)
                avg_n += arr_n[i];
            for (int i = 0; i < m; i++)
                avg_m += arr_m[i];
            Console.WriteLine("{0,2:f} {1,2:f}", avg_n / n, avg_m / m);
        }
    }
}

E 斐波那契

这道题目是本次赛组中比较难的一道题目, 递推公式已经给出并不困难, 主要是考虑到数据溢出的情况, 所以取余的话要分别把两个加数都取余

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            int n;
            int[] fn = new int[1000000];
            n = int.Parse(Console.ReadLine());
            if (n >= 1 && n <= 1000000)
            {
                fn[0] = 1; fn[1] = 1;
                for (int i = 2; i < n; i++)
                    fn[i] = (fn[i - 1] % 10007 + fn[i - 2] % 10007) % 10007;
                Console.WriteLine(fn[n - 1]);
            }
        }
    }
}

F yy的病

首先就是一个循环找出所有%7==0或是位数里带7的数并记录下来, 最后平方求和即可

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            int n;
            int i;
            while (int.TryParse(Console.ReadLine(),out n))
            {
                
                int sum = 0;
                for (i = 0; i <=n; i++)
                {
                    if (i % 7 == 0 || i % 10 == 7 || i / 10 == 7)
                        continue;
                    else
                        sum = sum + i * i;
                }
                Console.WriteLine(sum);
            }
        }
    }
}