试题A：门牌制作

#include<iostream>
using namespace std;

int main()
{
    int res = 0;
    for(int i = 1;i <= 2020;i ++)
    {
        int a = i % 10 , b = i / 10 % 10 ;
        int c = i / 100 % 10 , d = i / 1000;
        if(a == 2)  res ++;
        if(b == 2)  res ++;
        if(c == 2)  res ++;
        if(d == 2)  res ++;
    }
    cout<<res;
    return 0;
}

答案：624

试题B：既约分数

#include<iostream>
using namespace std;

int gcd(int x,int y)
{
    return y == 0 ? x : gcd(y,x%y);
}

int main()
{
    int res = 0;
    for(int i = 1;i <= 2020;i ++)
        for(int j = i;j <= 2020;j ++)
        {
            if(gcd(i,j) == 1 )
                res ++;
            if(i != j&&gcd(j,i) == 1)
                res ++;
        }
    cout<<res;
    return 0;
}

答案：2481215

试题C：蛇形填数

#include<iostream>
using namespace std;

int a[110][110];
int m = 1;

int main()
{
    for(int t = 0;t <= 100;t ++)
    {
        if(t % 2 == 1)
            for(int i = 0,j = t;i <= t;i ++,j --)
            {
                a[i][j] = m ++;
                //cout<<i<<" "<<j<<":"<<a[i][j]<<endl;
            }
        else
        {
            for(int i = t,j = 0;i >= 0;i --,j ++)
            {
                a[i][j] = m ++;
                //cout<<i<<" "<<j<<":"<<a[i][j]<<endl;
            }
        }
    }

    cout<<a[19][19];

    return 0;
}

答案：761

试题D：跑步锻炼

#include<iostream>
using namespace std;

int days[13] = {0,31,28,31,30,31,30,31,31,30,31,30,31};
int week = 6;

int main()
{
    int res = 0;
    for(int y = 2000;y <= 2020;y ++)
    {
        int leap = y % 4 == 0 && y % 100 || y % 400 == 0;
        for(int m = 1;m <= 12;m ++)
        {
            int sum = days[m];
            if(m == 2)  sum += leap;
            for(int d = 1;d <= sum;d ++)
            {
                if(d == 1 || week == 1) res += 1;
                res += 1;
                if(y == 2020 && m == 10 && d == 1 && week == 4)
                {
                    cout<<res;
                    return 0;
                }
                week ++;
                if(week > 7)    week = 1;
            }
        }   
    }
}

答案:8879

试题E：七段码

Updating...

答案:Updating...

试题F：成绩统计

#include <iostream>
#include <cstring>
#include <algorithm>
#define N 10010
using namespace std;

int q[N],n;

int main()
{
    cin>>n;
    float a = 0 , b = 0;
    for (int i = 0; i < n; i ++ )
    {
        cin>>q[i];
        if(q[i] >= 60)     a ++;
        if(q[i] >= 85 && q[i] <= 100)   b ++;
    }

    printf("%.f%% %.f%%",a/n*100,b/n*100);

    return 0;
}

试题G：回文日期

直接看我以前做的吧！我这里就不再重写了！
链接: https://www.acwing.com/solution/content/42745/

试题H：子串分值

听说暴力，能出奇迹！

#include <iostream>
#include <cstring>
#include <algorithm>
#include <unordered_map>

#define N 10010
using namespace std;

char s[N];
int temp[N];

int main()
{
    cin>>s;
    int res = 0 , len = strlen(s);
    for (int i = 0; i < len; i ++ )
    {
        memset(temp,0,sizeof temp);
        temp[s[i]] ++;
        int flag = 1;
        res ++;
        for (int j = i + 1; j < len; j ++ )
            if(!temp[s[j]])
            {
                flag++;
                temp[s[j]] ++;
                res += flag;
            }
            else
                res += flag;

    }

    cout<<res<<endl;

    return 0;
}

过了 60% 的数据

试题I：平面切分

越是最后的题，越短越恐怖。。。
反正AcWing上面通过率比较乐观！

试题J：字串排序

对于最后一道题，能骗就骗。。。
你要真执意搞懂，去CSDN上面看大佬的思考！