/*
::::
author:@DEANNOS at CODEFORCES 2022
::::
*/



#include <bits/stdc++.h>
//using policy based stl
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/trie_policy.hpp>
using namespace std;
#define endl "\n"
#define mod 1000000007
#define ll long long
#define ld long double
#define vi vector<int>
#define vll vector<ll>
#define pll pair<ll, ll>
#define pii pair<int, int>
#define ld  long double
#define ff  first
#define ss  second
#define vs  vector<string>
#define vpll vector<pll>
#define vb  vector<bool>
#define pb push_back
#define bg begin()
#define mp make_pair
#define ed end()
#define gi greater<int> ()
#define srt(v) (sort(all())
#define all(c) (c).begin(), (c).end()
#define sz(x) (int)(x).size()
#define fo(i,n) for(ll i=0;i<n;i++)
#define Fo(i,k,n) for(ll i=k;i<n;i++)
const int INF = 1000000000;
const int MAX_N = 2e5;



/*
int fastpower(int x, int y, int mod)
{
    int res = 1;
    x = x % mod;
    if (x == 0)
    {
     return 0;
    }
    while (y > 0)
    {
        if (y & 1)
        {
         res = (res*x) % mod;
        }
        y = y>>1;
        x = (x*x) % mod;
    }
    return res;
}
*/

/*
int GCD(int a,int b)
{
 while(b!=0)
 {
  int rem=a%b;
  a=b;
  b=rem;
 }
 return a;
}
*/

ll integer(ll a)
{
    return a >= 0 ? a : -a;
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int n;
    cin >> n;
    ll ans1 = 1, ans2 = 2, mx = 0;
    ll a;
    cin >> a;
    for (int i = 1; i < n; i++)
    {
        ll b;
        cin >> b;
        if (integr(a - b) > mx)
        {
            mx = integer(a - b);
            ans1 = i;
            ans2 = i + 1;
        }
        a = b;
    }
    cout << ans1 << ans2 << endl;
    return 0;

}

1) Maybe, you are reading long long variable with this command :
  scanf("%d",&arr[i]);
  It is not right. You should do, for example, it with next command
  scanf("%I64d",&arr[i]);
2) Maybe, you were confused by statement. You have to choose such two points so line that passing through this points has maximal absolute value of inclination, not just inclination.
3) Maybe, you are doing something like this :
    for ( int i = 1 ; i <= n ; ++i ) {
      long long d = abs2(arr[i+1] - arr[i]);

       if ( d > x ) {
                 x = d; m1 = i;
       }
   }
There is a mistake in first line. Right way is
   for ( int i = 1 ; i < n ; ++i ) {

It was my biggest mistake, because the problem itself is so simple.

[code deleted]

Edited by moderator 02.01.2020 18:17

In C++, you'd better use "long long" instead of "long".

What is test 3??? Help me!!! Please!!!

if 'a' and 'b' are both longint,abs(a-b) can be __int64.

AC)

Edited by author 21.07.2012 01:25

#include<iostream>
#include<cstdlib>
#include<cstdio>
#include<cmath>
long a[100000];
long b[100000];
long c[100000];
int d[100000];
using namespace std;
int main(){
    int n;
    int max;
    cin>>n;
    int i;
    for (i=0; i<n; i++){
        cin>>a[i];
        d[i]=1;
    }
    for (i=0; i<n-1; i++){
        float r=1+(a[i+1]-a[i])*(a[i+1]-a[i]);
        c[i]=sqrt(r);

    }
    for (i=0; i<n-2; i++){
       if ((a[i]-a[i+1])==(a[i+1]-a[i+2])){
            c[i+1]+=c[i];
            d[i+1]=d[i]+1;
            //cout<<d[i]<<" ";
       }
    }
    max=c[0];
    int t=0;
    for (i=0; i<n-1; i++){
        if (max<c[i]) {
            max=c[i];
            t=i;
        }
    }
//    cout<<d[0]<<" "<<d[1]<<" "<<d[2]<<" "<<d[3]<<" ";
    cout<<t+2-d[t]<<" "<<t+2;
    system("pause");
}

Why WA2? May be, someone had same problem?
My program here:

[code deleted]

Edited by author 28.03.2005 22:30

Edited by moderator 02.01.2020 18:24

This code gets WA on test 2:
[code deleted]

& this gets AC:
[code deleted]

:)

Edited by moderator 02.01.2020 18:26

Just change longint into int64.

C99 7.20.6.1: long long int llabs(long long int j);
but when I submit my code with use of llabs, I got CE.

If you use long long,ABS does not work,as this got WA on #2

[code deleted]

But this got AC!

[code deleted]

Edited by moderator 02.01.2020 18:27

remeber that "Each value of the function is longint (signed long in C++)",so if value[i]=-maxlongint and value[j]=maxlongint then abs(value[i]-value[j])>maxlongint
so DO use long long or int64.(i got WA just because of it for 10 times)

input
5
1
1
1
1
1
correct answer
1 2

I WAed many times for this........
RPWT..................-_-|||

囧。。。

i used long in java and got AC

1、The value of the function can be a real.
Use extended to solve the problem and you will get AC.
2、The progblem says that the line is above the points between the begining and the end of the line,not 'all of the points'.
May the force be with you.

RT