首先：

#include <iostream>
using namespace std;
int main()
{
    int n,sum;
    cin >> n;
    int a[n],s[n];
    for (int i = 0;i < n;i ++)
    {
        cin >> a[i];
        s[i] = 0;
    }
    for (int i = 1;i < n;i ++)
    {
        s[abs(a[i] - a[i - 1])] = 1;
    }
    for (int i = 1;i < n;i ++)
    {
        if (s[i] == 0)
        {
            cout << "Not jolly";
            return 0;
        }
    }
    cout << "jolly";
    return 0;
}

#	1	2	3	4	5	6	7	8	9	X
结果	WA	AC	RE	WA	WA	WA	RE	WA	RE	RE

仔细可以发现cout << jolly不对

于是……

#include <iostream>
using namespace std;
int main()
{
    int n,sum;
    cin >> n;
    int a[n],s[n];
    for (int i = 0;i < n;i ++)
    {
        cin >> a[i];
        s[i] = 0;
    }
    for (int i = 1;i < n;i ++)
    {
        s[abs(a[i] - a[i - 1])] = 1;
    }
    for (int i = 1;i < n;i ++)
    {
        if (s[i] == 0)
        {
            cout << "Not jolly";
            return 0;
        }
    }
    cout << "Jolly";
    return 0;
}

#	1	2	3	4	5	6	7	8	9	X
结果	AC	AC	RE	AC	AC	AC	RE	AC	RE	RE

然后……

我就不会了T_T