fn main() { let (e, ask) = read(); let n = e.len() + 1; let mut val = (1..=(n as i32)).collect::>(); let p = val.iter().enumerate().map(|p| (*p.1, p.0 as i32)).collect::>(); let mut solver = RerootingDP::new( R, p, e.into_iter().map(|e| (e.0, e.1, ())).collect::>(), ); let mut ans = vec![0; ask.len()]; let mut pre = 0; for (ans, (u, v)) in ans.iter_mut().zip(ask) { let u = (u + pre) % n; let v = (v + pre) % n; val.swap(u, v); solver.set_vertex(u, (val[u], u as i32)); solver.set_vertex(v, (val[v], v as i32)); let p = solver.find(u); *ans = p.2 + 1; pre = *ans as usize; } use util::*; println!("{}", ans.iter().join("\n")); } struct R; impl TreeDP for R { type Vertex = (i32, i32); type Edge = (); // パスの始点、繋がってるなら次の頂点、端 type Path = (i32, i32, i32); // パスの始点、終端 type Point = (i32, i32); fn vertex(&self, v: &Self::Vertex) -> Self::Path { (v.0, 0, v.1) } fn add_edge(&self, p: &Self::Path, e: &Self::Edge) -> Self::Point { (p.0, p.2) } fn rake(&self, a: &Self::Point, b: &Self::Point) -> Self::Point { std::cmp::max(*a, *b) } fn add_vertex(&self, p: &Self::Point, v: &Self::Vertex) -> Self::Path { (v.0, p.0, p.1) } fn compress(&self, p: &Self::Path, c: &Self::Path, e: &Self::Edge) -> Self::Path { if p.1 >= 0 && c.0 > p.1 { (p.0, c.1, c.2) } else { (p.0, -1, p.2) } } } fn read() -> (Vec<(usize, usize)>, Vec<(usize, usize)>) { let mut s = String::new(); use std::io::*; std::io::stdin().read_to_string(&mut s).unwrap(); let mut it = s.trim().split_whitespace().flat_map(|s| s.parse::()); let mut next = || it.next().unwrap(); let n = next(); let e = (1..n) .map(|_| { let a = next() - 1; let b = next() - 1; (a, b) }) .collect(); let q = next(); let ask = (0..q) .map(|_| { let a = next() - 1; let b = next() - 1; (a, b) }) .collect(); (e, ask) } pub trait TreeDP { type Vertex: Clone; type Edge: Clone; type Path: Clone; type Point: Clone; fn vertex(&self, v: &Self::Vertex) -> Self::Path; fn add_edge(&self, p: &Self::Path, e: &Self::Edge) -> Self::Point; fn rake(&self, a: &Self::Point, b: &Self::Point) -> Self::Point; fn add_vertex(&self, p: &Self::Point, v: &Self::Vertex) -> Self::Path; fn compress(&self, p: &Self::Path, c: &Self::Path, e: &Self::Edge) -> Self::Path; } pub struct RerootingDP { op: R, v: Vec, e: Vec, sum: Vec>, stt: StaticTopTree, } impl RerootingDP where R: TreeDP, { const ROOT: usize = 0; pub fn new(op: R, v: Vec, edge: Vec<(usize, usize, R::Edge)>) -> Self { assert!(v.len() == edge.len() + 1); let mut e = vec![]; let mut memo = vec![]; for (a, b, w) in edge { e.push(w); memo.push((a, b)); } let stt = StaticTopTree::new(memo, Self::ROOT); let sum = vec![Union::V((op.vertex(&v[0]), op.vertex(&v[0]))); stt.label.len()]; let mut res = Self { op, v, e, sum, stt }; for i in 0..res.stt.label.len() { res.pull(i); } res } pub fn set_vertex(&mut self, v: usize, w: R::Vertex) { self.v[v] = w; self.update(self.stt.vertex[v]); } pub fn set_edge(&mut self, e: usize, w: R::Edge) { self.e[e] = w; self.update(self.stt.edge[e]); } pub fn find(&self, root: usize) -> R::Path { if root == Self::ROOT { return self.sum.last().unwrap().get_v().0.clone(); } // なんか非常に汚い、もっと綺麗に書けないか let mut pos = self.stt.vertex[root]; let mut memo = vec![]; while let Some(p) = self.stt.node[pos].p.get() { let l = self.stt.node[p].l.get().unwrap() == pos; pos = p; memo.push((p, l)); } let mut up: Option<(R::Path, R::Edge)> = None; let mut down: Option<(R::Path, R::Edge)> = None; let mut point: Option = None; let mut vertex: Option = None; for &(pos, left) in memo.iter().rev() { if self.stt.label[pos] == STTLabel::Compress { let e = &self.e[self.stt.node[pos].e.get().unwrap()]; if left { let r = self.stt.node[pos].r.get().unwrap(); let r = &self.sum[r].get_v().0; down = Some(down.map_or((r.clone(), e.clone()), |(a, b)| { (self.op.compress(r, &a, &b), e.clone()) })); } else { let l = self.stt.node[pos].l.get().unwrap(); let l = &self.sum[l].get_v().1; up = Some(up.map_or((l.clone(), e.clone()), |(a, b)| { (self.op.compress(l, &a, &b), e.clone()) })); } } else if self.stt.label[pos] == STTLabel::AddVertex { vertex = Some(self.v[self.stt.node[pos].e.get().unwrap()].clone()); let u = up.take().map(|p| self.op.add_edge(&p.0, &p.1)); let d = down.take().map(|p| self.op.add_edge(&p.0, &p.1)); point = match (u, d) { (Some(a), Some(b)) => Some(self.op.rake(&a, &b)), (a, b) => a.or(b), }; } else if self.stt.label[pos] == STTLabel::Rake { let other = if left { self.stt.node[pos].r } else { self.stt.node[pos].l } .get() .unwrap(); let p = self.sum[other].get_e(); point = Some(point.map_or(p.clone(), |q| self.op.rake(p, &q))); } else if self.stt.label[pos] == STTLabel::AddEdge { let e = &self.e[self.stt.node[pos].e.get().unwrap()]; if point.is_some() { let p = point.take().unwrap(); let v = vertex.take().unwrap(); up = Some((self.op.add_vertex(&p, &v), e.clone())); } else { unreachable!() } } else { unreachable!() } } let pos = self.stt.vertex[root]; if self.stt.label[pos] == STTLabel::AddVertex { let u = up.map(|p| self.op.add_edge(&p.0, &p.1)); let d = down.map(|p| self.op.add_edge(&p.0, &p.1)); let p = match (u, d) { (Some(a), Some(b)) => Some(self.op.rake(&a, &b)), (a, b) => a.or(b), } .unwrap(); let c = self.sum[self.stt.node[pos].l.get().unwrap()].get_e(); let q = self.op.rake(&p, c); self.op.add_vertex(&q, &self.v[root]) } else { let u = up.map(|p| self.op.add_edge(&p.0, &p.1)); let d = down.map(|p| self.op.add_edge(&p.0, &p.1)); let p = match (u, d) { (Some(a), Some(b)) => Some(self.op.rake(&a, &b)), (a, b) => a.or(b), } .unwrap(); self.op.add_vertex(&p, &self.v[root]) } } fn update(&mut self, mut v: usize) { self.pull(v); while let Some(p) = self.stt.node[v].p.get() { v = p; self.pull(p); } } fn pull(&mut self, v: usize) { match self.stt.label[v] { STTLabel::Vertex => { let u = self.stt.node[v].e.get().unwrap(); let p = self.op.vertex(&self.v[u]); self.sum[v].set_v((p.clone(), p)); } STTLabel::AddEdge => { let l = self.stt.node[v].l.get().unwrap(); let e = self.stt.node[v].e.get().unwrap(); let path = &self.sum[l].get_v().0; let point = self.op.add_edge(path, &self.e[e]); self.sum[v].set_e(point); } STTLabel::Rake => { let l = self.stt.node[v].l.get().unwrap(); let r = self.stt.node[v].r.get().unwrap(); let point = self.op.rake(self.sum[l].get_e(), self.sum[r].get_e()); self.sum[v].set_e(point); } STTLabel::AddVertex => { let l = self.stt.node[v].l.get().unwrap(); let u = self.stt.node[v].e.get().unwrap(); let path = self.op.add_vertex(self.sum[l].get_e(), &self.v[u]); self.sum[v].set_v((path.clone(), path)); } STTLabel::Compress => { let l = self.sum[self.stt.node[v].l.get().unwrap()].get_v(); let r = self.sum[self.stt.node[v].r.get().unwrap()].get_v(); let e = self.stt.node[v].e.get().unwrap(); let lr = self.op.compress(&l.0, &r.0, &self.e[e]); let rl = self.op.compress(&r.1, &l.1, &self.e[e]); self.sum[v].set_v((lr, rl)); } } } } pub struct FixRootTreeDP { op: R, v: Vec, e: Vec, sum: Vec>, stt: StaticTopTree, } impl FixRootTreeDP where R: TreeDP, { pub fn new(op: R, v: Vec, edge: Vec<(usize, usize, R::Edge)>) -> Self { assert!(v.len() == edge.len() + 1); let mut e = vec![]; let mut memo = vec![]; for (a, b, w) in edge { e.push(w); memo.push((a, b)); } let stt = StaticTopTree::new(memo, 0); let sum = vec![Union::V(op.vertex(&v[0])); stt.label.len()]; let mut res = Self { op, v, e, sum, stt }; for i in 0..res.stt.label.len() { res.pull(i); } res } pub fn set_vertex(&mut self, v: usize, w: R::Vertex) { self.v[v] = w; self.update(self.stt.vertex[v]); } pub fn set_edge(&mut self, e: usize, w: R::Edge) { self.e[e] = w; self.update(self.stt.edge[e]); } pub fn find(&self) -> R::Path { self.sum.last().unwrap().get_v().clone() } fn update(&mut self, mut v: usize) { self.pull(v); while let Some(p) = self.stt.node[v].p.get() { v = p; self.pull(p); } } fn pull(&mut self, v: usize) { match self.stt.label[v] { STTLabel::Vertex => { let u = self.stt.node[v].e.get().unwrap(); self.sum[v].set_v(self.op.vertex(&self.v[u])); } STTLabel::AddEdge => { let l = self.stt.node[v].l.get().unwrap(); let e = self.stt.node[v].e.get().unwrap(); let path = self.sum[l].get_v(); let point = self.op.add_edge(path, &self.e[e]); self.sum[v].set_e(point); } STTLabel::Rake => { let l = self.stt.node[v].l.get().unwrap(); let r = self.stt.node[v].r.get().unwrap(); let point = self.op.rake(self.sum[l].get_e(), self.sum[r].get_e()); self.sum[v].set_e(point); } STTLabel::AddVertex => { let l = self.stt.node[v].l.get().unwrap(); let u = self.stt.node[v].e.get().unwrap(); let path = self.op.add_vertex(self.sum[l].get_e(), &self.v[u]); self.sum[v].set_v(path); } STTLabel::Compress => { let l = self.sum[self.stt.node[v].l.get().unwrap()].get_v(); let r = self.sum[self.stt.node[v].r.get().unwrap()].get_v(); let e = self.stt.node[v].e.get().unwrap(); let path = self.op.compress(l, r, &self.e[e]); self.sum[v].set_v(path); } } } } #[derive(Clone, Debug)] enum Union { V(V), E(E), } impl Union { fn set_v(&mut self, v: V) { *self = Self::V(v); } fn set_e(&mut self, e: E) { *self = Self::E(e); } fn get_v(&self) -> &V { let Union::V(ref v) = self else { unreachable!() }; v } fn get_e(&self) -> &E { let Union::E(ref v) = self else { unreachable!() }; v } } #[derive(Debug, Clone, Copy, Eq, PartialEq)] enum STTLabel { Vertex, AddEdge, Rake, AddVertex, Compress, } #[derive(Clone, Debug)] struct STTNode { p: Pointer, l: Pointer, r: Pointer, e: Pointer, } impl STTNode { fn new(l: Pointer, r: Pointer, e: Pointer) -> Self { Self { p: Pointer::null(), l, r, e, } } } pub struct StaticTopTree { label: Vec, node: Vec, height: Vec, vertex: Vec, edge: Vec, size: usize, } impl StaticTopTree { pub fn new(edge: Vec<(usize, usize)>, root: usize) -> Self { let size = edge.len() + 1; let mut graph = vec![vec![]; size]; for (i, &(a, b)) in edge.iter().enumerate() { graph[a].push((b, i)); graph[b].push((a, i)); } let mut topo = vec![root]; let mut parent = vec![(size, size); size]; let mut inv_edge = vec![size; size]; for i in 0..size { let v = topo[i]; for (u, k) in graph[v].clone() { graph[u].retain(|p| p.0 != v); parent[u] = (v, k); inv_edge[k] = u; topo.push(u); } } let mut s = vec![1i32; size]; for &v in topo.iter().rev() { let c = &mut graph[v]; for i in 1..c.len() { if s[c[i].0] > s[c[0].0] { c.swap(0, i); } } s[v] += c.iter().map(|e| s[e.0]).sum::(); } let mut stt = Self { label: vec![], node: vec![], height: vec![], vertex: vec![!0; size], edge: vec![!0; size - 1], size, }; let mut id = vec![!0; size]; for &v in topo.iter().rev() { if graph[v].len() <= 1 { id[v] = stt.append_inner(!0, !0, v, STTLabel::Vertex); } else { let mut array = vec![None; 64]; let mut bit = 0usize; for &(u, e) in graph[v][1..].iter() { let mut k = stt.append_inner(id[u], !0, e, STTLabel::AddEdge); let mut h = stt.height[k]; while let Some(x) = array[h].take() { bit ^= 1 << h; k = stt.append_inner(k, x, !0, STTLabel::Rake); h = stt.height[k]; } array[h] = Some(k); bit |= 1 << h; } let x = bit.trailing_zeros() as usize; let mut k = array[x].take().unwrap(); bit ^= 1 << x; while bit > 0 { let x = bit.trailing_zeros() as usize; let u = array[x].take().unwrap(); k = stt.append_inner(k, u, !0, STTLabel::Rake); bit ^= 1 << x; } id[v] = stt.append_inner(k, !0, v, STTLabel::AddVertex); } if v == root || graph[parent[v].0][0].0 != v { let mut stack = vec![(id[v], size)]; let mut pos = v; while let Some(&(u, k)) = graph[pos].get(0) { stack.push((id[u], k)); while stack.len() > 1 { let len = stack.len(); let (b, a) = (stack[len - 2], stack[len - 1]); if len >= 3 && stt.height[stack[len - 3].0] <= stt.height[a.0] { let c = stack[len - 3]; stack.truncate(len - 3); let v = stt.append_inner(c.0, b.0, b.1, STTLabel::Compress); stack.extend([(v, c.1), a].iter().cloned()); } else if stt.height[b.0] <= stt.height[a.0] { stack.truncate(len - 2); let v = stt.append_inner(b.0, a.0, a.1, STTLabel::Compress); stack.push((v, b.1)); } else { break; } } pos = u; } while stack.len() >= 2 { let a = stack.pop().unwrap(); let b = stack.pop().unwrap(); let v = stt.append_inner(b.0, a.0, a.1, STTLabel::Compress); stack.push((v, b.1)); } id[v] = stack.pop().unwrap().0; } } stt } fn append_inner(&mut self, l: usize, r: usize, e: usize, label: STTLabel) -> usize { let v = self.node.len(); let mut h = 0; let lp = if let Some(n) = self.node.get_mut(l) { n.p.set(v); h = std::cmp::max(h, self.height[l]); Pointer::new(l) } else { Pointer::null() }; let rp = if let Some(n) = self.node.get_mut(r) { n.p.set(v); h = std::cmp::max(h, self.height[r]); Pointer::new(r) } else { Pointer::null() }; if self.node.get(r).is_some() { h += 1; } let ep = if e < self.size { if label == STTLabel::Vertex || label == STTLabel::AddVertex { self.vertex[e] = v; } else if label == STTLabel::AddEdge || label == STTLabel::Compress { self.edge[e] = v; } else { unreachable!(); } Pointer::new(e) } else { Pointer::null() }; self.label.push(label); self.node.push(STTNode::new(lp, rp, ep)); self.height.push(h); v } } // ---------- begin pointer ---------- #[derive(Clone, Copy)] pub struct Pointer(u32); impl Pointer { pub fn new(v: usize) -> Self { Self(v as u32) } pub fn null() -> Self { Self(!0) } pub fn get(&self) -> Option { if self.0 == !0 { None } else { Some(self.0 as usize) } } pub fn is_null(&self) -> bool { self.get().is_none() } pub fn set(&mut self, v: usize) { self.0 = v as u32 } } impl From for Pointer { fn from(x: usize) -> Self { Self::new(x) } } impl Default for Pointer { fn default() -> Self { Self::null() } } impl std::fmt::Debug for Pointer { fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { if let Some(x) = self.get() { write!(f, "{}", x) } else { write!(f, "null") } } } // ---------- end pointer ---------- mod util { pub trait Join { fn join(self, sep: &str) -> String; } impl Join for I where I: Iterator, T: std::fmt::Display, { fn join(self, sep: &str) -> String { let mut s = String::new(); use std::fmt::*; for (i, v) in self.enumerate() { if i > 0 { write!(&mut s, "{}", sep).ok(); } write!(&mut s, "{}", v).ok(); } s } } }