[ZJOI2008]树的统计 【树链剖分】

[ZJOI2008]树的统计

感觉树剖是我打过要调最少的数据结构了

询问就一直顺着链走就好

代码

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#define ll long long 
#define lo o<<1
#define ro o<<1|1
#define mid ((l+r)>>1)
using namespace std;
const ll N=30010, infmin=-0x7f7f7f;
ll n, m, rt, w[N];
ll tot, id[N], real[N], top[N], siz[N], fa[N], dep[N], hson[N];

ll to[N<<1], next[N<<1], head[N<<1], now;
void add(ll u, ll v) {to[++now]=v; next[now]=head[u]; head[u]=now;to[++now]=u; next[now]=head[v]; head[v]=now;}

ll sum[N<<2], maxn[N<<2], laz[N<<2];
void pushup(ll o) {sum[o]=sum[lo]+sum[ro]; maxn[o]=max(maxn[lo], maxn[ro]);}
void build(ll o, ll l, ll r)
{   
    maxn[o]=infmin; if(l == r) {sum[o]=maxn[o]=w[real[l]]; return ;}
    build(lo, l, mid); build(ro, mid+1, r); pushup(o);
}
void updata(ll o, ll l, ll r, ll X, ll x)
{
    if(X > r || X < l) return ; if(l == r) {maxn[o]=sum[o]=x; return ;}
    updata(lo, l, mid, X, x); updata(ro, mid+1, r, X, x); pushup(o);
}
ll querysum(ll o, ll l, ll r, ll L, ll R)
{
    if(l > R || r < L) return 0; if(l >= L && r <= R) return sum[o];
    return querysum(lo, l, mid, L, R)+querysum(ro, mid+1, r, L, R);
}
ll querymaxn(ll o, ll l, ll r, ll L, ll R)
{
    if(l > R || r < L) return infmin; if(l >= L && r <= R) return maxn[o];
    return max(querymaxn(lo, l, mid, L, R), querymaxn(ro, mid+1, r, L, R));
}

void dfs1(ll u, ll f)
{
    fa[u]=f, siz[u]=1; ll v;
    for(ll i=head[u]; i; i=next[i]) if((v=to[i]) != fa[u])
        {dep[v]=dep[u]+1; dfs1(v, u); siz[u]+=siz[v]; if(!hson[u] || siz[v] > siz[hson[u]]) hson[u]=v;}
}
void dfs2(ll u, ll anc)
{
    top[u]=anc; id[u]=++tot; real[tot]=u; ll v;
    if(!hson[u]) return ; dfs2(hson[u], anc);
    for(ll i=head[u]; i; i=next[i]) if((v=to[i]) != fa[u] && v != hson[u]) dfs2(v, v);
}
ll Querymaxn(ll u, ll v)
{
    ll tu=top[u], tv=top[v], ans=infmin; 
    while(tu != tv)
    {
        if(dep[tu] < dep[tv]) swap(tu, tv), swap(u, v);
        ans=max(ans, querymaxn(1, 1, n, id[tu], id[u])); u=fa[tu], tu=top[u];
    }
    if(dep[u] > dep[v]) swap(u, v);  ans=max(ans, querymaxn(1, 1, n, id[u], id[v]));
    return ans;
}
ll Querysum(ll u, ll v)
{
    ll tu=top[u], tv=top[v], ans=0; 
    while(tu != tv)
    {
        if(dep[tu] < dep[tv]) swap(tu, tv), swap(u, v); 
        ans+=querysum(1, 1, n, id[tu], id[u]); u=fa[tu], tu=top[u];
    }
    if(dep[u] > dep[v]) swap(u, v);  ans+=querysum(1, 1, n, id[u], id[v]);
    return ans;
}

ll read(){
    ll out=0, f=1; char c=getchar(); while(c < '0' || c > '9') {if(c == '-') f=-1; c=getchar();}
    while(c >= '0' && c <= '9') {out=(out<<1)+(out<<3)+c-'0'; c=getchar();}
    return out*f;
}

void solve()
{
    for(int i=1; i <= m; i++)
    {
        string cmd; cin>>cmd; ll a=read(), b=read();
        if(cmd == "CHANGE") updata(1, 1, n, id[a], b);
        if(cmd == "QMAX") printf("%lld\n", Querymaxn(a, b));
        if(cmd == "QSUM") printf("%lld\n", Querysum(a, b));
    }
}

ll mark[N], mn, u, v;

void init()
{
    n=read();  
    for(ll i=1; i < n; i++) mark[u=read()]++, mark[v=read()]++, add(u, v); 
    for(ll i=1; i <= n; i++) {w[i]=read(); if(mark[i] > mn) rt=i, mn=mark[i];}
    dfs1(rt, 0); dfs2(rt, rt); build(1, 1, n); m=read();
}

int main()
{
    init(); solve();
    return 0;
}