整齐的数组

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whiteawll 2022-08-16 14:44:31 博主文章分类：练习题目 ©著作权

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http://oj.daimayuan.top/course/11/problem/554
#include<bits/stdc++.h>
using namespace std;

#define rep(i,l,r) for(int i=(l);i<=(r);i++)
#define per(i,l,r) for(int i=(l);i>=(r);i--)
#define ll long long
#define mset(s,t) memset(s,t,sizeof(t))
#define mcpy(s,t) memcpy(s,t,sizeof(t))
#define fi first
#define se second
#define pb push_back
#define all(x) (x).begin(),(x).end()
#define SZ(x) ((int)(x).size())
#define mp make_pair

typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;   
typedef vector<ll> Vll;               
typedef vector<pair<int, int> > vpii;
typedef vector<pair<ll, ll> > vpll;                        

const ll mod = 1e9 + 7;
//const ll mod = 998244353;
const double pi  = acos(-1.0);

inline ll qmi (ll a, ll b) {
    ll ans = 1;
    while (b) {
        if (b & 1) ans = ans * a%mod;
        a = a * a %mod;
        b >>= 1;
    }
    return ans;
}
inline int read () {
    int x = 0, f = 0;
    char ch = getchar();
    while (!isdigit(ch)) f |= (ch=='-'),ch= getchar();
    while (isdigit(ch)) x = x * 10 + ch - '0', ch = getchar();
    return f?-x:x;
}
template<typename T> void print(T x) {
    if (x < 0) putchar('-'), x = -x;
    if (x >= 10) print(x/10);
    putchar(x % 10 + '0');
}
inline ll sub (ll a, ll b) {
    return ((a - b ) %mod + mod) %mod;
}
inline ll add (ll a, ll b) {
    return (a + b) %mod;
}
inline ll inv (ll a) {
    return qmi(a, mod - 2);
}
vector<ll> dif;

bool check(int x) {
    for (auto t : dif) {
        if (t % x != 0) return 0;
    }
    return 1;
}
void solve() {
    dif.clear();
    int n;
    cin >> n;
    vector<int> a(n);
    map<int, int> cnt;
    int kind = 0, minv = 0x3f3f3f3f;
    for (int i = 0; i < n; i ++)
    {
        cin >> a[i];
        minv = min (minv, a[i]);
        cnt[a[i]] ++;
        if (cnt[a[i]] == 1) kind ++;
    }
    for (int i = 0; i < n; i ++) {
        if (a[i] == minv) continue;
        dif.pb(a[i] - minv);
    }
    if (kind == 1) {
        puts("-1");
    }
    else {
        sort(all(dif));
        
        ll ans = 0;
        vector<ll> yinzi;
        yinzi.pb(1);
        yinzi.pb(dif[0]);
        for (ll i = 2; i <= dif[0] / i; i ++) {
            if (dif[0] % i == 0) {
                yinzi.pb(dif[0] / i);
                yinzi.pb(i);
            }
        }
        for (auto t : yinzi) {
            
            bool f = 1;
            for (int j = 0; j < dif.size(); j ++) {
                if (dif[j] % t != 0) {
                    f = 0;
                    
                }
            }
            if (f) ans = max (ans, t);
        }
        cout << ans << endl;
    }
}
int main () {
    // ios::sync_with_stdio(0),cin.tie(0), cout.tie(0);
    int t;
    t =1;
    cin >> t;
    while (t --) solve();
    return 0;
}