85 lines
2.2 KiB
C++
85 lines
2.2 KiB
C++
#include<bits/stdc++.h>
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using namespace std;
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const int mod = 998244353;
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int n, m, k;
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int up;
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vector<int> fri[300005];
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int fa[3000005];
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int cnt[300005];
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int son[300005];
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int dfn[300005];
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int rev[300005];
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int top[300005];
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int dep[300005];
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int nowdfn;
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struct SEG{
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int num[51][1200005];
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void init(int now, int nl, int nr) {
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if(nl == nr) {
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num[0][now] = 1;
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for(int i = 1; i <= 50; ++i)
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num[i][now] = (1ll * num[i - 1][now] * dep[rev[nl]]) % mod;
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return;
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}
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int nmid = (nl + nr) >> 1;
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init(now * 2, nl, nmid);
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init(now * 2 + 1, nmid + 1, nr);
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for(int i = 1; i <= 50; ++i) num[i][now] = (1ll * num[i][now * 2] + num[i][now * 2 + 1]) % mod;
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}
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int query(int now, int nl, int nr, int l, int r) {
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if(nl > r || nr < l) return 0;
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if(l <= nl && nr <= r) return num[k][now];
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int nmid = (nl + nr) >> 1;
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return (1ll * query(now * 2, nl, nmid, l, r) + query(now * 2 + 1, nmid + 1, nr, l, r)) % mod;
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}
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}seg;
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void dfs1(int now, int from) {
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cnt[now] = 1;
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for(int i : fri[now]) {
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if(i == from) continue;
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fa[i] = now;
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dep[i] = dep[now] + 1;
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dfs1(i, now);
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cnt[now] += cnt[i];
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if(cnt[i] > cnt[son[now]]) son[now] = i;
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}
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}
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void dfs2(int now, int from) {
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dfn[now] = ++nowdfn;
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rev[nowdfn] = now;
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top[now] = from;
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if(son[now]) dfs2(son[now], from);
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for(int i : fri[now]) {
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if(i == fa[now] || i == son[now]) continue;
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dfs2(i, i);
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}
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}
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int query(int a, int b) {
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int ans = 0;
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while(top[a] != top[b]) {
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if(dep[top[a]] < dep[top[b]]) swap(a, b);
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ans = (ans + 1ll * seg.query(1, 1, n, dfn[top[a]], dfn[a])) % mod;
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a = fa[top[a]];
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}
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if(dep[a] < dep[b]) swap(a, b);
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ans = (ans + 1ll * seg.query(1, 1, n, dfn[b], dfn[a])) % mod;
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return ans;
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}
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int main() {
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scanf("%d", &n);
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for(int i = 1, u, v; i < n; ++i) {
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scanf("%d%d", &u, &v);
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fri[u].push_back(v);
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fri[v].push_back(u);
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}
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dfs1(1, 0);
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dfs2(1, 1);
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seg.init(1, 1, n);
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scanf("%d", &m);
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for(up = 1; up <= m; ++up) {
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int i, j;
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scanf("%d%d%d", &i, &j, &k);
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printf("%d\n", query(i, j));
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}
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return 0;
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} |