思路：好裸的LCA呀。

#include
     
      #define LL long long#define fi first#define se second#define mk make_pair#define PII pair
      
       #define y1 skldjfskldjg#define y2 skldfjsklejgusing namespace std;const int N = 5e5 + 7;const int M = 1e7 + 7;const int inf = 0x3f3f3f3f;const LL INF = 0x3f3f3f3f3f3f3f3f;const int mod = 1000000007;int n, m, f[N][21], depth[N];vector
       
         edge[N];void dfs(int u, int fa, int deep) {    depth[u] = deep;    f[u][0] = fa;    for(int i = 1; i < 21; i++)        f[u][i] = f[f[u][i - 1]][i - 1];    for(int i = 0; i < edge[u].size(); i++) {        int v = edge[u][i];        if(v == fa) continue;        dfs(v, u, deep + 1);    }}PII cal(int u, int v) {    if(depth[u] < depth[v]) swap(u, v);    int ans = 0;    for(int i = 20; i >= 0; i--) {        if(!f[u][i]) continue;        if(depth[f[u][i]] < depth[v]) continue;        u = f[u][i];        ans += (1 << i);    }    if(u == v) return mk(u, ans);    for(int i = 20; i >= 0; i--) {        if(!f[u][i] || !f[v][i]) continue;        if(f[u][i] == f[v][i]) continue;        u = f[u][i]; v = f[v][i];        ans += 2 * (1 << i);    }    return mk(f[u][0], ans + 2);}int main() {    scanf("%d%d", &n, &m);    for(int i = 1; i < n; i++) {        int u, v;        scanf("%d%d", &u, &v);        edge[u].push_back(v);        edge[v].push_back(u);    }    dfs(1, 0, 0);    while(m--) {        int x, y, z;        scanf("%d%d%d", &x, &y, &z);        PII ans = mk(inf, 0);        PII t1 = cal(x, y), t2 = cal(x, z), t3 = cal(y, z);        ans = min(ans, mk(t1.se + cal(t1.fi, z).se, t1.fi));        ans = min(ans, mk(t2.se + cal(t2.fi, y).se, t2.fi));        ans = min(ans, mk(t3.se + cal(t3.fi, x).se, t3.fi));        printf("%d %d\n", ans.se, ans.fi);    }    return 0;}/**/