4539: [Hnoi2016]树

4539: [Hnoi2016]树

链接

分析：

　　主席树+倍增。

代码：

#include<cstdio>
#include<algorithm>
#include<cstring>
#include<iostream>
#include<cmath>
#include<cctype>
#include<set>
#include<queue>
#include<vector>
#include<map>
#define pa pair<int,int>
using namespace std;
typedef long long LL;
#define int LL
inline int read() {
    int x=,f=;char ch=getchar();for(;!isdigit(ch);ch=getchar())if(ch=='-')f=-;
    for(;isdigit(ch);ch=getchar())x=x*+ch-'';return x*f;
}

const int N = ;
struct Edge { int to, nxt; } e[N << ];
struct OPT { int l, r, fa, rt; } q[N];
int head[N], dfn[N], st[N], ed[N], pos[N], fa[N][], siz[N], f[N][], g[N][], d1[N], d2[N];
set< pa > s;
int En, Index, NowIndex, n;

inline void add_edge(int u,int v) {
    ++En; e[En].to = v, e[En].nxt = head[u]; head[u] = En;
    ++En; e[En].to = u, e[En].nxt = head[v]; head[v] = En;
}
struct SegmentTree{
    int sum[N * ], ls[N * ], rs[N * ], Root[N], TreeIndex;
    void Insert(int l,int r,int &now,int pre,int p) {
        if (!now) now = ++TreeIndex;
        sum[now] = sum[pre] + ;
        if (l == r) return ;
        int mid = (l + r) >> ;
        if (p <= mid) {
            rs[now] = rs[pre];
            Insert(l, mid, ls[now], ls[pre], p);
        } else {
            ls[now] = ls[pre];
            Insert(mid + , r, rs[now], rs[pre], p);
        }
    }
    int query(int l,int r,int H,int T,int k) {
        if (l == r) return l;
        int mid = (l + r) >> ;
        if (k <= sum[ls[T]] - sum[ls[H]]) return query(l, mid, ls[H], ls[T], k);
        else return query(mid + , r, rs[H], rs[T], k - (sum[ls[T]] - sum[ls[H]]));
    }
}T;
void dfs(int u) {
    d1[u] = d1[fa[u][]] + ;
    st[u] = ++Index; pos[Index] = u; siz[u] = ;
    for (int i = ; i <= ; ++i) fa[u][i] = fa[fa[u][i - ]][i - ];
    for (int i = head[u]; i; i = e[i].nxt) {
        int v = e[i].to;
        if (v == fa[u][]) continue;
        fa[v][] = u;
        dfs(v);
        siz[u] += siz[v];
    }
    ed[u] = Index;
}
int LCA1(int u,int v) {
    if (d1[u] < d1[v]) swap(u, v);
    int d = d1[u] - d1[v];
    for (int i = ; ~i; --i) if ((d >> i) & ) u = fa[u][i];
    if (u == v) return u;
    for (int i = ; ~i; --i) if (fa[u][i] != fa[v][i]) u = fa[u][i], v = fa[v][i];
    return fa[u][];
}
int getdis(int x,int y) {
    return d1[x] + d1[y] - d1[LCA1(x, y)] * ;
}
void add(int id) {
    int x = read(), y = read(), z;
    q[id].l = NowIndex, q[id].r = (NowIndex += siz[x]) - , q[id].rt = x;
    set< pa > :: iterator it = s.lower_bound(pa(y, )); z = q[it->second].rt;
    q[id].fa = T.query(, n, T.Root[st[z] - ], T.Root[ed[z]], y - q[it->second].l + );
    f[id][] = it->second, g[id][] = getdis(q[id].fa, z) + ;
    d2[id] = d2[it->second] + ;
    for (int i = ; i <= ; ++i) f[id][i] = f[f[id][i - ]][i - ], g[id][i] = g[id][i - ] + g[f[id][i - ]][i - ];
    s.insert(pa(q[id].r, id));
}
int LCA2(int u,int v,int tu,int tv) {
    if (d2[u] < d2[v]) swap(u, v), swap(tu, tv);
    int ans = , t = u, d = d2[u] - d2[v];
    for (int i = ; ~i; --i) if ((d >> i) & ) ans += g[u][i], u = f[u][i];
    if (u == v) {
        d --; ans = ; u = t;
        for (int i = ; ~i; --i) if ((d >> i) & ) ans += g[t][i], t = f[t][i];
        ans += getdis(q[t].fa, tv) +  + getdis(tu, q[u].rt);
        return ans;
    }
    ans += getdis(tu, q[t].rt) + getdis(tv, q[v].rt);
    for (int i = ; ~i; --i) if (f[u][i] != f[v][i]) ans += g[u][i] + g[v][i], u = f[u][i], v = f[v][i];
    ans += getdis(q[u].fa, q[v].fa) + ;
    return ans;
}
void Ask() {
    int u = read(), v = read(), ans, iu, iv, tu, tv;
    iu = s.lower_bound(pa(u, ))->second, iv = s.lower_bound(pa(v, ))->second;
    tu = T.query(, n, T.Root[st[q[iu].rt] - ], T.Root[ed[q[iu].rt]], u - q[iu].l + );
    tv = T.query(, n, T.Root[st[q[iv].rt] - ], T.Root[ed[q[iv].rt]], v - q[iv].l + );
    if (iu != iv) ans = LCA2(iu, iv, tu, tv);
    else ans = getdis(tu, tv);
    printf("%lld\n", ans);
}
signed main() {
    n = read();int m = read(), Q = read();
    for (int i = ; i < n; ++i) add_edge(read(), read());
    dfs();
    for (int i = ; i <= n; ++i)
        T.Insert(, n, T.Root[i], T.Root[i - ], pos[i]);
    NowIndex = n + ;
    s.insert(pa(n, )); q[].l = , q[].r = n, q[].rt = , q[].fa = ;
    for (int i = ; i <= m; ++i) add(i + );
    while (Q --) Ask();
    return ;
}