黑黑白白

比较明显的SG函数。
设d[x]表示先手轮到x点时的取胜情况。
当子状态有必败状态时，该状态为必胜状态。
当子状态全部为必胜状态，该状态为必败状态。

#include <bits/stdc++.h>
#include <unordered_map>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;

#ifdef LOCAL
#define debug(x) cout << "[" __FUNCTION__ ": " #x " = " << (x) << "]\n"
#define TIME cout << "RuningTime: " << clock() << "ms\n", 0
#else
#define TIME 0
#endif
#define hash_ 1000000009
#define Continue(x) { x; continue; }
#define Break(x) { x; break; }
const int mod = 998244353;
const int N = 1e4 + 10;
const int INF = 0x3f3f3f3f;
const ll LINF = 0x3f3f3f3f3f3f3f3f;
#define gc p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, 1000000, stdin), p1 == p2) ? EOF : *p1++;
inline int read(){ static char buf[1000000], *p1 = buf, *p2 = buf; register int x = false; register char ch = gc; register bool sgn = false; while (ch != '-' && (ch < '0' || ch > '9')) ch = gc; if (ch == '-') sgn = true, ch = gc; while (ch >= '0'&& ch <= '9') x = (x << 1) + (x << 3) + (ch ^ 48), ch = gc; return sgn ? -x : x; }
ll fpow(ll a, int b, int mod) { ll res = 1; for (; b > 0; b >>= 1) { if (b & 1) res = res * a % mod; a = a * a % mod; } return res; }
vector<int>G[N];
int sg[N];
void dfs(int x, int fa)
{
    int flag = 1;
    for (auto &i : G[x])
    {
        if (i == fa)
            continue;
        dfs(i, x);
        flag &= sg[i];
    }
    if (!flag)
        sg[x] = 1;
}

int main()
{
#ifdef LOCAL
    freopen("E:/input.txt", "r", stdin);
#endif
    int kcase = 0;
    int t;
    cin >> t;
    while (t--)
    {
        memset(sg, 0, sizeof sg);
        int n, m;
        scanf("%d%d", &n, &m);
        for (int i = 1; i < n; i++)
        {
            int u, v;
            scanf("%d%d", &u, &v);
            G[u].push_back(v);
            G[v].push_back(u);
        }
        dfs(m, -1);
        if (sg[m])
            puts("Gen");
        else
            puts("Dui");
        for (int i = 1; i <= n; i++)
            G[i].clear();
    }
    return TIME;
}