#include<stdio.h>
#include<math.h>

int main(){
int n;
scanf("%d",&n);

if(n==0){printf("%d",1);}
else if(n>0){printf("%d",(n*(n+1))/2);}
else{
        n=fabs(n);
        printf("%d",-1*(((n*(n+1))/2)-1));
    }

return 0;
}

Who can give me an AC program?

maybe it is not the best solution, but

using System;
using System.Collections.Generic;

namespace _1026
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            List<int> z = new List<int>();
            for(int i = 0; i < n; i++)
                z.Add(int.Parse(Console.ReadLine()));
            z.Sort();
            Console.ReadLine();
            int k = int.Parse(Console.ReadLine());
            for (int i = 0; i < k; i++)
                Console.WriteLine(z[int.Parse(Console.ReadLine())-1]);

        }
    }
}

#include <iostream>
#include <set>
using namespace std;
int main() {
    int index = 0, cnt = 0, n;
    set<string> a, b, c;
    a.insert("Alice");
    a.insert("Ariel");
    a.insert("Aurora");
    a.insert("Peter");
    a.insert("Phil");
    a.insert("Olaf");
    a.insert("Phoebus");
    a.insert("Ralph");
    a.insert("Robin");
    b.insert("Bambi");
    b.insert("Belle");
    b.insert("Bolt");
    b.insert("Mulan");
    b.insert("Mowgli");
    b.insert("Mickey");
    b.insert("Silver");
    b.insert("Simba");
    b.insert("Stitch");
    c.insert("Dumbo");
    c.insert("Genie");
    c.insert("Jiminy");
    c.insert("Kuzko");
    c.insert("Kida");
    c.insert("Kenai");
    c.insert("Tarzan");
    c.insert("Tiana");
    c.insert("Winnie");
    cin >> n;
    int a1=0,b1=1,c1=2;
    for(int i = 0; i < n; i++)
    {
        string ask;
        cin >> ask;
        if(*a.find(ask) == ask)
        {
            cnt += abs(index - a1);
            index = a1;
        }
        if(*b.find(ask) == ask)
        {
            cnt += abs(index - b1);
            index = b1;
        }
        if(*c.find(ask) == ask)
        {
            cnt += abs(index - c1);
            index = c1;
        }

    }
    cout << cnt;

}

Test:
9
001110000
101111001

Thanks :)

using System;

class Test
{
    public static void Main()
    {
        String strB = "";
        String strA = "";

        int num = Convert.ToInt32(Console.ReadLine());
        int b = 1;

        for (int a = num; a > 0; a--)
        {
            strA = StrAMaker(a);

            strB = ')' + strA + '+' + b + strB;
            b++;
        }
        string s3 = new string('(', --num);
        strB = s3 + strB.TrimStart(')');
        Console.WriteLine(strB);
    }

    public static string StrAMaker (int a)
    {
        string s1 = new string(')', a);
        String s2 = "";

        for (int i = 1; i <= a; i++)
        {
            if (i % 2 == 0)
            {
                s2 = s2 + "sin(" + i + "+";
                if (i == a) s2 = s2.TrimEnd('+') + s1;
            }
            else
            {
                s2 = s2 + "sin(" + i + "-";
                if (i == a) s2 = s2.TrimEnd('-') + s1;
            }
        }

        return s2;
    }
}

#include <iostream>
using namespace std;
int main()
{
     int n,m,teacher[1500],student[100000],same=0;
    cin>>n;
    for(int i=0;i<n;i++)
        cin>>teacher[i];
    cin>>m;
    for(int i=0;i<m;i++)
        cin>>student[i];

    for(int i=0;i<n;i++)
        for(int j=0;j<m;j++)
            if(teacher[i]==student[j]) same++;

    cout<<same;
    return 0;
}

write 7 test. Please.

Can someone send test 6 please? Thanks

Edited by author 26.11.2019 11:33

I used sqrt-decomposition and got AC in 358ms

My idea was like this:
1. Keep an array of the elements we have so far
2. For each sqrt-size block of the array compute the GCD
3. To insert an element: append it to the array and update its block
4. To remove an element: swap the element to be deleted with last element (I used a set of pairs<value, index> to get them quickly) and update their blocks

Insert (sqrt n)
Delete (sqrt n)
O(q sqrt n) where n is number of elements in the array

please can anyone tell me what is the test of 5.

#include <iostream>
#include <string>
using namespace std;
int main()
{
    int n,g=2;
    cin >> n;
    for(int i = 0; i < n; i++)
    {
        string a;
        cin >> a;
        if(a.length() > 4 && a.substr(a.length()-4,a.length()-1) == "+one")
            g+=2;
        else
            g++;
    }
    if(g == 13)
        cout << 1400;
    else
        cout << g*100;
}

Can you send me test 11?

I can't understand what's wrong with my code
is my algorithm wrong? or what?
my code:

#include <stdio.h>
#include <math.h>
double x[102],y[102];

double dist(int i, int j){
    int d1=abs(x[i]-x[j]),d2=abs(y[i]-y[j]);
    if(d1==0)
        return (d2);
    else if(d2==0)
      return (d1);
    else
      return sqrt(d1*d1 + d2*d2);
}

int main(){
    int i;
    double n,s=0,r,pi=2*acos(0);
  scanf("%Lf %Lf",&n,&r);
  for(i=0;i<n;i++)
      scanf("%Lf %Lf",&x[i],&y[i]);
    for(i=1;i<n;i++)
        s+=dist(i,i-1);
    s+=dist(0,n-1);
    s+=2*pi*r;
    printf("%.2Lf\n",s);
  return 0;
}

if someone can help me I would appreciate very much
thanks!

Edited by author 17.11.2019 11:13

Can anyone help me? I have no idea about how this test looks like.

Any hints or tests?

So, when user starts looking for words, my program immediately writes the answer. Maybe that's why it isn't correct. For example:
user -> 2
user -> ab
program -> abc
user -> xz
program -> xzy