Bzoj4568: [Scoi2016]幸运数字
2018-03-16 22:14
337 查看
题面
传送门Sol
裸的线性基当然是选择\(log^3\)的\(st\)表+树剖辣
# include <bits/stdc++.h> # define RG register # define IL inline # define Fill(a, b) memset(a, b, sizeof(a)) using namespace std; typedef long long ll; const int _(2e4 + 5); IL ll Input(){ RG ll x = 0, z = 1; RG char c = getchar(); for(; c < '0' || c > '9'; c = getchar()) z = c == '-' ? -1 : 1; for(; c >= '0' && c <= '9'; c = getchar()) x = (x << 1) + (x << 3) + (c ^ 48); return x * z; } int n, q, lg[_], first[_], cnt; struct Edge{ int to, next; } edge[_ << 1]; ll pw[63] = {1}, w[_]; struct Bac{ ll b[63]; int num; IL void Init(){ Fill(b, 0); } IL void Insert(RG ll x){ if(num == 63) return; for(RG int i = 62; ~i; --i){ if(~x & pw[i]) continue; if(!x) break; if(!b[i]){ b[i] = x, ++num; break; } x ^= b[i]; } } IL ll Calc(){ RG ll x = 0; for(RG int i = 62; ~i; --i) x = max(x, x ^ b[i]); return x; } } st[20][_], Ans; IL Bac operator +(RG Bac A, RG Bac B){ for(RG int i = 62; ~i; --i) if(A.b[i]) B.Insert(A.b[i]); return B; } IL void Add(RG int u, RG int v){ edge[cnt] = (Edge){v, first[u]}, first[u] = cnt++; } int dfn[_], fa[_], top[_], size[_], son[_], idx, deep[_]; IL void Dfs1(RG int u){ size[u] = 1; for(RG int e = first[u]; e != -1; e = edge[e].next){ RG int v = edge[e].to; if(size[v]) continue; deep[v] = deep[u] + 1, fa[v] = u; Dfs1(v); size[u] += size[v]; if(size[v] > size[son[u]]) son[u] = v; } } IL void Dfs2(RG int u, RG int Top){ top[u] = Top, dfn[u] = ++idx; if(son[u]) Dfs2(son[u], Top); for(RG int e = first[u]; e != -1; e = edge[e].next) if(!dfn[edge[e].to]) Dfs2(edge[e].to, edge[e].to); } IL void Build(){ for(RG int i = 2; i <= n; ++i) lg[i] = lg[i >> 1] + 1; Dfs1(1), Dfs2(1, 1); for(RG int i = 1; i <= n; ++i) st[0][dfn[i]].Insert(w[i]); for(RG int j = 1; j <= lg ; ++j) for(RG int i = 1; i + (1 << j) - 1 <= n; ++i) st[j][i] = st[j - 1][i] + st[j - 1][i + (1 << (j - 1))]; } IL Bac Query(RG int l, RG int r){ RG int lg2 = lg[r - l + 1]; return st[lg2][l] + st[lg2][r - (1 << lg2) + 1]; } IL Bac LCA(RG int u, RG int v){ Ans.Init(); while(top[u] ^ top[v]){ if(deep[top[u]] < deep[top[v]]) swap(u, v); Ans = Ans + Query(dfn[top[u]], dfn[u]); u = fa[top[u]]; } if(deep[u] > deep[v]) swap(u, v); return Ans + Query(dfn[u], dfn[v]); } int main(RG int argc, RG char *argv[]){ for(RG int i = 1; i < 63; ++i) pw[i] = pw[i - 1] << 1; n = Input(), q = Input(); for(RG int i = 1; i <= n; ++i) w[i] = Input(), first[i] = -1; for(RG int i = 1; i < n; ++i){ RG int u = Input(), v = Input(); Add(u, v), Add(v, u); } Build(); for(RG int i = 1; i <= q; ++i){ RG int u = Input(), v = Input(); printf("%lld\n", LCA(u, v).Calc()); } return 0; }
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