JZOJ 6176 「GDOI2019」滑稽二乘法

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因为身体不舒服所以来写 GDOI 的防 AK 题了（？

首先把 \(1\) 抽出来当根。
记 \(\def\fa{ {\rm fa} } \fa_k(u)\) 表示 \(u\) 的 \(k\) 级祖先。
记 \(\def\dep{ {\rm dep} } \dep(u)\) 表示 \(u\) 到根的距离。
记 \(f_i(u)\) 表示 \(u\) 子树内的黑点与 \(u\) 的距离的 \(i\) 次方和（\(i \in \{0,1,2\}\)）。

对于一次询问，设 \(w = {\rm LCA}(u,v)\)。
分类讨论所有黑点与 \(\def\Path{ {\rm Path} } \Path(u,v)\) 最近的点为哪个点。

若其在 \(w\) 子树外，则意味着在 \(w\) 处取到距离的最小值。
考虑 \(\fa_k(w)\) 的贡献，则其为 \[ \begin{aligned} f_2(\fa_k(w)) &- (f_2(\fa_{k-1}(w))+2f_1(\fa_{k-1}(w))+f_0(\fa_{k-1}(w))) \\ &+ 2k(f_1(\fa_k(w))-f_1(\fa_{k-1}(w))-f_0(\fa_{k-1}(w))) \\ &+ k^2(f_0(\fa_k(w))-f_0(\fa_{k-1}(w))) \end{aligned} \]

讲人话就是在 \(\fa_k(w)\) 子树内但不在 \(\fa_{k-1}(w)\) 子树内的黑点的贡献。

对于 \(k=1\dots \dep(w)\) 对上式求和可得 \[ \begin{aligned} f_2(1) &+2\dep(w)f_1(1)+\dep^2(w)f_0(1) \\ &-f_2(w)-4\sum\limits_{k=0}^{\dep(w)-1}(f_1(\fa_k(w))+(k+1)f_0(\fa_k(w))) \end{aligned} \]

若其为 \(\Path(u,w)\) 上的点，设 \(s = \dep_u - \dep_w\)，则考虑 \(\fa_k(u)\) 的贡献： \[ f_2(\fa_k(u))-(f_2(\fa_{k-1}(u))+2f_1(\fa_{k-1}(u))+f_0(\fa_{k-1}(u))) \]

对于 \(k=0\dots \dep(u)-\dep(w)-1\) 对上式求和得 \[ -\sum\limits_{k=0}^{\dep(u)-\dep(w)-1} (2f_1(\fa_k(u))+f_0(\fa_k(u))) \]

同理可得 \(\Path(v,w)\) 上的贡献，再加上在 \(w\) 子树内但不在 \(u,v\) 子树内的贡献，综合可得 \[ \begin{aligned} f_2(1) &+2\dep(w)f_1(1)+\dep^2(w)f_0(1) \\ &-4\sum\limits_{k=0}^d (f_1(\fa_k(w))+(k+1)f_0(\fa_k(w))) \\ &-\sum\limits_{k=0}^s (2f_1(\fa_k(u))+f_0(\fa_k(u))) \\ &-\sum\limits_{k=0}^t (2f_1(\fa_k(v))+f_0(\fa_k(v))) \end{aligned} \]

其中 \(d = \dep(w)-1,s = \dep(u)-\dep(w)-1,t = \dep(v)-\dep(w)-1\)。

到这一步其实已经可以维护了，但是由于我比较懒，所以考虑搞出一个更好维护的形式。
记 \(g_i(u)\) 表示 \(u\) 子树内黑点 \(\dep\) 值的 \(i\) 次方和。
则显然 \[ f_0(u)=g_0(u),f_1(u)=g_1(u)-\dep(u)g_0(u) \]

代入原式再一顿乱化可得 \[ \begin{aligned} f_2(1) &+2\dep(w)f_1(1)+\dep^2(w)f_0(1) \\ &-4\sum\limits_{k=0}^d g_1(\fa_k(w)) \\ &-4(\dep(w)+1)\sum\limits_{k=0}^d g_0(\fa_k(w)) \\ &+8\sum\limits_{k=0}^d \dep(\fa_k(w)) g_0(\fa_k(w)) \\ &-2\sum\limits_{k=0}^s g_1(\fa_k(u)) \\ &+2\sum\limits_{k=0}^s \dep(\fa_k(u))g_0(\fa_k(u)) \\ &-\sum\limits_{k=0}^s g_0(\fa_k(u)) \\ &-2\sum\limits_{k=0}^t g_1(\fa_k(v)) \\ &+2\sum\limits_{k=0}^t \dep(\fa_k(v))g_0(\fa_k(v)) \\ &-\sum\limits_{k=0}^t g_0(\fa_k(v)) \end{aligned} \]

那么需要支持维护 \(g_0(u),\dep(u)g_0(u),g_1(u)\)，比较简单。
JZOJ 卡栈传统艺能。

代码： 

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#pragma GCC optimize("Ofast")
#pragma GCC target("sse3","sse2","sse")
#pragma GCC diagnostic error "-std=c++14"
#pragma GCC diagnostic error "-fwhole-program"
#pragma GCC diagnostic error "-fcse-skip-blocks"
#pragma GCC diagnostic error "-funsafe-loop-optimizations"
#pragma GCC optimize("fast-math","unroll-loops","no-stack-protector","inline")
#include <cstdio>
#include <utility>
#include <algorithm>
using namespace std;
const int N = 1e5;
const int mod = 998244353;
int n,m;
int to[(N << 1) + 5],pre[(N << 1) + 5],first[N + 5];
inline void add(int u,int v)
{
    static int tot = 0;
    to[++tot] = v,pre[tot] = first[u],first[u] = tot;
}
int col[N + 5];
int sum[3];
int fa[N + 5],dep[N + 5],sz[N + 5],son[N + 5],top[N + 5],id[N + 5],rk[N + 5];
int cur[N + 5];
void dfs1()
{
    for(register int p = 1,flag;;)
    {
        flag = 0;
        if(!sz[p])
            sz[p] = 1,cur[p] = first[p];
        for(register int i = cur[p];i;i = pre[i])
        {
            cur[p] = pre[i];
            if(to[i] ^ fa[p])
            {
                fa[to[i]] = p,dep[to[i]] = dep[p] + 1;
                p = to[i],flag = 1;
                break;
            }
        }
        if(!flag)
        {
            if(!fa[p])
                break;
            else
                sz[fa[p]] += sz[p],
                (!son[fa[p]] || sz[son[fa[p]]] < sz[p]) && (son[fa[p]] = p),
                p = fa[p];
        }
    }
}
void dfs2()
{
    int tot = 0;
    top[1] = 1;
    for(register int p = 1,flag;;)
    {
        flag = 0;
        if(!id[p])
        {
            rk[id[p] = ++tot] = p,cur[p] = first[p];
            if(son[p])
            {
                top[son[p]] = top[p],p = son[p];
                continue;
            }
        }
        for(register int i = cur[p];i;i = pre[i])
        {
            cur[p] = pre[i];
            if(to[i] ^ fa[p] && to[i] ^ son[p])
            {
                top[to[i]] = to[i];
                p = to[i],flag = 1;
                break;
            }
        }
        if(!flag)
        {
            if(!fa[p])
                break;
            else
                p = fa[p];
        }
    }
}
namespace HLD
{
    #define ls (p << 1)
    #define rs (ls | 1)
    struct node
	{
        int d;
        int g0,dg0,g1;
        int tag0,tag1;
    } seg[(N << 2) + 5];
    void build(int p,int tl,int tr)
	{
        if(tl == tr)
        {
            seg[p].d = dep[rk[tl]];
            return ;
        }
        int mid = tl + tr >> 1;
        build(ls,tl,mid),build(rs,mid + 1,tr);
        seg[p].d = (seg[ls].d + seg[rs].d) % mod;
    }
    void update(int l,int r,int k0,int k1,int p,int tl,int tr)
	{
        if(l <= tl && tr <= r)
        {
            seg[p].g0 = (seg[p].g0 + (long long)(tr - tl + 1) * k0) % mod,
            seg[p].dg0 = (seg[p].dg0 + (long long)seg[p].d * k0) % mod,
            seg[p].g1 = (seg[p].g1 + (long long)(tr - tl + 1) * k1) % mod,
            seg[p].tag0 = (seg[p].tag0 + k0) % mod,
            seg[p].tag1 = (seg[p].tag1 + k1) % mod;
            return ;
        }
        int mid = tl + tr >> 1;
        l <= mid && (update(l,r,k0,k1,ls,tl,mid),1);
        r > mid && (update(l,r,k0,k1,rs,mid + 1,tr),1);
        seg[p].g0 = (seg[ls].g0 + seg[rs].g0) % mod,
        seg[p].g0 = (seg[p].g0 + (long long)(tr - tl + 1) * seg[p].tag0) % mod,
        seg[p].dg0 = (seg[ls].dg0 + seg[rs].dg0) % mod,
        seg[p].dg0 = (seg[p].dg0 + (long long)seg[p].d * seg[p].tag0) % mod,
        seg[p].g1 = (seg[ls].g1 + seg[rs].g1) % mod,
        seg[p].g1 = (seg[p].g1 + (long long)(tr - tl + 1) * seg[p].tag1) % mod;
    }
    typedef pair< pair<int,int>,pair<int,int> > value;
    inline value operator+(const value &a,const value &b)
    {
        return value(make_pair((a.first.first + b.first.first) % mod,(a.first.second + b.first.second) % mod),make_pair((a.second.first + b.second.first) % mod,(a.second.second + b.second.second) % mod));
    }
    value query(int l,int r,int p,int tl,int tr)
	{
        if(l > r)
            return value(make_pair(0,0),make_pair(0,0));
        if(l <= tl && tr <= r)
            return value(make_pair(seg[p].g0,seg[p].dg0),make_pair(seg[p].g1,seg[p].d));
        int mid = tl + tr >> 1;
        value ret(make_pair(0,0),make_pair(0,0));
        l <= mid && (ret = ret + query(l,r,ls,tl,mid),1);
        r > mid && (ret = ret + query(l,r,rs,mid + 1,tr),1);
        ret = ret + value(make_pair((long long)(min(r,tr) - max(l,tl) + 1) * seg[p].tag0 % mod,(long long)ret.second.second * seg[p].tag0 % mod),make_pair((long long)(min(r,tr) - max(l,tl) + 1) * seg[p].tag1 % mod,0));
        return ret;
    }
    int getlca(int x,int y)
	{
        while(top[x] ^ top[y])
            dep[top[x]] > dep[top[y]] ? (x = fa[top[x]]) : (y = fa[top[y]]);
        return dep[x] < dep[y] ? x : y;
    }
    void update(int p,int k)
	{
        sum[0] = (sum[0] + k) % mod,
        sum[1] = (sum[1] + (long long)k * dep[p]) % mod,
        sum[2] = (sum[2] + (long long)k * dep[p] % mod * dep[p]) % mod;
        for(register int x = p;top[x];x = fa[top[x]])
            update(id[top[x]],id[x],k,(long long)k * dep[p] % mod,1,1,n);
    }
    value query(int p,int u)
	{
        value ret(make_pair(0,0),make_pair(0,0));
        if(dep[p] <= dep[u])
            return ret;
        for(;top[p] ^ top[u];p = fa[top[p]])
            ret = ret + query(id[top[p]],id[p],1,1,n);
        ret = ret + query(id[u] + 1,id[p],1,1,n);
        return ret;
    }
}
int ans;
int main()
{
    freopen("regress.in","r",stdin),freopen("regress.out","w",stdout);
    scanf("%d",&n);
    int u,v;
    for(register int i = 1;i < n;++i)
        scanf("%d%d",&u,&v),add(u,v),add(v,u);
    dfs1(),dfs2(),HLD::build(1,1,n);
    int op,w;
    HLD::value t;
    for(scanf("%d",&m);m;--m)
    {
        scanf("%d%d",&op,&u);
        if(!op)
            HLD::update(u,col[u] ? mod - 1 : 1),col[u] ^= 1;
        else
        {
            scanf("%d",&v),w = HLD::getlca(u,v);
            ans = (sum[2] + 2LL * dep[w] * sum[1] + (long long)dep[w] * dep[w] % mod * sum[0]) % mod,
            ans = (mod - ans) % mod;
            t = HLD::query(w,1),
            ans = (ans + 4LL * (dep[w] + 1) % mod * t.first.first) % mod,
            ans = (ans - 8LL * t.first.second + 8LL * mod) % mod,
            ans = (ans + 4LL * t.second.first) % mod;
            t = HLD::query(u,w),
            ans = (ans + t.first.first) % mod,
            ans = (ans - 2LL * t.first.second + 2LL * mod) % mod,
            ans = (ans + 2LL * t.second.first) % mod;
            t = HLD::query(v,w),
            ans = (ans + t.first.first) % mod,
            ans = (ans - 2LL * t.first.second + 2LL * mod) % mod,
            ans = (ans + 2LL * t.second.first) % mod;
            ans = (mod - ans) % mod;
            printf("%d\n",ans);
        }
    }
}