纯暴力 = 25 分

建议在OJ上评测时加上 assert，爱护评测机。。

比赛时那就让程序撒丫子跑，说不定就多过几个点。

#include <bits/stdc++.h>
using namespace std;
const int MAXK = 4;
const int MAXN = 50000;
int T, k;
int n, ans;
int p[MAXN + 5];
int a[MAXK + 5][MAXN + 5];
int cMax[MAXK + 5], cMin[MAXK + 5];
void dfs(int now)
{
    if (now > n)
    {
        for (int i = 0; i <= k - 1; i++)
            cMax[i] = cMin[i] = a[i][1];
        for (int i = 2; i <= n; i++)
            for (int j = 0; j < k; j++)
                cMax[j] = max(cMax[j], a[(j + p[i]) % k][i]),
                cMin[j] = min(cMin[j], a[(j + p[i]) % k][i]);
        /*
        cout << "======\n";
        for(int i=1;i<=n;i++)
            cout<<p[i]<<" ";
            cout<<"---\n";
        for (int j = 0; j <= k - 1; j++)
        {
            cout<<cMax[j]<<":"<<cMin[j]<<" ";
            for (int i = 1; i <= n; i++)
            {
                cout << a[(j + p[i]) % k][i] << " ";
            }
            cout << "\n";
        }
        */
        int now = 0;
        for (int i = 0; i < k; i++)
            now = max(now, cMax[i] - cMin[i]);
        // cout << "= " << now << "\n";
        ans = min(ans, now);
        return;
    }
    for (int i = 0; i < k; i++)
    {
        p[now] = i;
        dfs(now + 1);
    }
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin >> T >> k;
    while (T--)
    {
        cin >> n;
        assert(k == 1 || n <= 20);
        for (int j = 0; j <= k - 1; j++)
            for (int i = 1; i <= n; i++)
                cin >> a[j][i];
        // a[j][1] 固定，a[j][2~n] 枚举所有可能性
        // 第 i 个拨圈的第 j 行为 a[(j + p[i]) % k][i]
        p[1] = 0;
        ans = 30005;
        dfs(2);
        cout << ans << "\n";
    }
    return 0;
}