1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130
| #include<bits/stdc++.h>
using namespace std; #define ll long long const int INF = 0x3f3f3f3f; const int N = 2e5 + 10; const ll mod = 998244353;
int n, k, q; vector<int> G[N]; int a[N]; ll ans[2000000];
bool vis[N]; int siz[N];
int get_sz(int u, int _fa) { siz[u] = 1; for (int v:G[u]) { if (v == _fa || vis[v])continue; siz[u] += get_sz(v, u); } return siz[u]; }
typedef pair<int, int> pii;
pii get_rt(int u, int _fa, int tot) { pii res = pii(INF, -1); int s = 1, m = 0; for (int v:G[u]) { if (v == _fa || vis[v])continue; res = min(res, get_rt(v, u, tot)); m = max(m, siz[v]); s += siz[v]; } m = max(m, tot - s); res = min(res, pii(m, u)); return res; }
struct Q { int s, t, id; }; vector<Q> qrys[N];
vector<int> T[N]; int fa[N], dep[N];
int build(int u, int _fa, int d) { get_sz(u, 0); int rt = get_rt(u, 0, siz[u]).second; vis[rt] = 1; dep[rt] = d; for (int v:G[rt]) { if (vis[v] || v == _fa)continue; int vrt = build(v, rt, d + 1); T[rt].push_back(vrt); fa[vrt] = rt; } return rt; }
int LCA(int u, int v) { if (dep[u] < dep[v])swap(u, v); while (dep[u] > dep[v])u = fa[u]; while (u != v)u = fa[u], v = fa[v]; return u; }
ll f[N][55];
void getf(int u, int _fa) { for (int v:G[u]) { if (v == _fa || vis[v])continue; fill(f[v], f[v] + k, 0); for (int i = 0; i < k; i++) { f[v][i] = (f[v][i] + f[u][i]) % mod; f[v][(i + a[v]) % k] = (f[v][(i + a[v]) % k] + f[u][i]) % mod; } getf(v, u); } }
void solve(int rt) { vis[rt] = 1; fill(f[rt], f[rt] + k, 0); f[rt][0] = 1; getf(rt, 0); for (Q o:qrys[rt]) { int s = o.s, t = o.t, id = o.id; if (s == rt) { ans[id] = (f[t][0] + f[t][(k - a[rt]) % k]) % mod; } else { for (int i = 0; i < k; i++) { ans[id] = (ans[id] + f[s][i] * f[t][(k - i) % k] % mod) % mod; ans[id] = (ans[id] + f[s][i] * f[t][(k - i - a[rt] + k) % k] % mod) % mod; } } } for (int v:T[rt]) { if (vis[v])continue; solve(v); } }
int main() { scanf("%d%d", &n, &k); 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); } for (int i = 1; i <= n; i++)scanf("%d", &a[i]); build(1, 0, 1); scanf("%d", &q); for (int i = 1; i <= q; i++) { int s, t; scanf("%d%d", &s, &t); qrys[LCA(s, t)].push_back(Q{s, t, i}); } memset(vis, 0, sizeof(vis)); get_sz(1, 0); int root = get_rt(1, 0, siz[1]).second; memset(vis, 0, sizeof(vis)); solve(root); for (int i = 1; i <= q; i++)printf("%lld\n", ans[i]); return 0; }
|