调了几个小时555

record: https://www.luogu.com.cn/record/201530666

$\text{\#16 Time Limit Exceeded. 1.20s/5.54MB}$

$\textit{My Code}$:

#include <bits/stdc++.h>
using namespace std;
const int MAXN = 5e3, MAXS = 1e6;
//快读
inline int read()
{
    static char c;
    while (c = getchar(), !isdigit(c))
        ;
    int res = c - 48;
    while (c = getchar(), isdigit(c))
        res = (res << 3) + (res << 1) + c - 48;
    return res;
}
int n, s[MAXN + 1], d[MAXN * MAXN + 1], siz, maxb, i, j, ptr;
bool b[MAXS + 1], flag;
int main()
{
    n = read();
    for (i = 1; i <= n; ++i)
    {
        s[i] = read();
        for (j = 1; j < i; ++j)
            b[abs(s[i] - s[j])] = true, maxb = max(maxb, abs(s[i] - s[j]));
    }
    for (i = 1; i <= maxb; ++i)
        if (b[i])
            d[siz++] = i;
    for (ptr = 0, i = n, flag = false; !flag; ++i)
    {
        flag = true;
        while (d[ptr++] < i)
            ;
        for (j = --ptr; j < siz && flag; ++j)
            if (!(d[j] % i))
                flag = false;
    }
    cout << i - 1 << endl;
    return 0;
}

大佬教教这位可怜的蒟蒻吧