P3241 [HNOI2015]开店 题解

const int N=1.5e5+13,logN=21;
struct Edge{int v,w,nxt;}e[N<<1];
int n,m,q,a[N],h[N],etot;
int siz[N],maxx[N],rt,psum,fa[N],dep[N];
ll dis[N][logN];
bool vis[N];
std::vector<pii> d[N],ch[N];
std::vector<ll> sd[N],sch[N];
inline void add_edge(int u,int v,int w){e[++etot]=(Edge){v,w,h[u]};h[u]=etot;}

namespace Tree{
int fa[N],dep[N],siz[N],son[N],top[N];ll dis[N];
void dfs1(int u,int f,int deep){
	dep[u]=deep,siz[u]=1,fa[u]=f;
	for(int i=h[u];i;i=e[i].nxt){
		int v=e[i].v;if(v==f) continue;
		dis[v]=dis[u]+e[i].w;
		dfs1(v,u,deep+1);
		siz[u]+=siz[v];
		if(siz[v]>siz[son[u]]) son[u]=v;
	}
}
void dfs2(int u,int topf){
	top[u]=topf;
	if(!son[u]) return;
	dfs2(son[u],topf);
	for(int i=h[u];i;i=e[i].nxt){
		int v=e[i].v;
		if(v!=fa[u]&&v!=son[u]) dfs2(v,v);
	}
}
inline void init(){dfs1(1,0,0);dfs2(1,1);}
inline int lca(int u,int v){
	while(top[u]!=top[v]){
		if(dep[top[u]]<dep[top[v]]) swap(u,v);
		u=fa[top[u]];
	}
	return dep[u]<dep[v]?u:v;
}
inline ll dist(int u,int v){return dis[u]+dis[v]-2*dis[lca(u,v)];}
}

void findrt(int u,int f){
	siz[u]=1,maxx[u]=0;
	for(int i=h[u];i;i=e[i].nxt){
		int v=e[i].v;if(v==f||vis[v]) continue;
		findrt(v,u);
		siz[u]+=siz[v];
		maxx[u]=max(maxx[u],siz[v]);
	}
	maxx[u]=max(maxx[u],psum-siz[u]);
	if(maxx[u]<maxx[rt]) rt=u;
}
void dfs(int u,int f,ll dis,int g1,int g2){
	d[g1].pb(mp(a[u],dis)),ch[g2].pb(mp(a[u],dis));
	for(int i=h[u];i;i=e[i].nxt){
		int v=e[i].v;
		if(v!=f&&!vis[v]) dfs(v,u,dis+e[i].w,g1,g2);
	}
}
void build(int u){
	vis[u]=1;
	ch[u].pb(mp(a[u],0));
	for(int i=h[u];i;i=e[i].nxt){
		int v=e[i].v;if(vis[v]) continue;
		rt=0,psum=siz[v];
		findrt(v,0),findrt(rt,0);
		fa[rt]=u,dep[rt]=dep[u]+1;
		dfs(v,0,e[i].w,rt,u);
		build(rt);
	}
	std::sort(ch[u].begin(),ch[u].end());
	std::sort(d[u].begin(),d[u].end());
//	printf("debug:%d\n",u);
//	for(auto v:ch[u]) printf("age=%d dis=%lld\n",v.fi,v.se);
//	printf("\n");
	ll now=0;
	for(int j=0,lim=ch[u].size();j<lim;++j) now+=ch[u][j].se,sch[u].pb(now);
	now=0;
	for(int j=0,lim=d[u].size();j<lim;++j) now+=d[u][j].se,sd[u].pb(now);
}
int main(){
	read(n),read(q),read(m);
	for(int i=1;i<=n;++i) read(a[i]);
	for(int i=1;i<n;++i){
		int u,v,w;read(u),read(v),read(w);
		add_edge(u,v,w),add_edge(v,u,w);
	}
	maxx[rt=0]=INF,psum=n;
	findrt(1,0),findrt(rt,0);
	build(rt);
	Tree::init();
	for(int i=1;i<=n;++i)
		for(int j=fa[i];j;j=fa[j]) dis[i][dep[i]-dep[j]]=Tree::dist(i,j);
	ll lastans=0;
	while(q--){
		int x,l,r;read(x),read(l),read(r);
		l=(l+lastans)%m,r=(r+lastans)%m;if(l>r) swap(l,r);pii tmpl=mp(l,-LLINF),tmpr=mp(r,LLINF);
		int L=std::lower_bound(ch[x].begin(),ch[x].end(),tmpl)-ch[x].begin();
		int R=std::lower_bound(ch[x].begin(),ch[x].end(),tmpr)-ch[x].begin()-1;
		ll ans=0;
		if(R>=0) ans=sch[x][R]-(L>0?sch[x][L-1]:0);
		for(int u=x;fa[u];u=fa[u]){
			L=std::lower_bound(ch[fa[u]].begin(),ch[fa[u]].end(),tmpl)-ch[fa[u]].begin();
			R=std::lower_bound(ch[fa[u]].begin(),ch[fa[u]].end(),tmpr)-ch[fa[u]].begin()-1;
			if(R>=0) ans+=sch[fa[u]][R]-(L>0?sch[fa[u]][L-1]:0)+(R-L+1)*dis[x][dep[x]-dep[fa[u]]];
			L=std::lower_bound(d[u].begin(),d[u].end(),tmpl)-d[u].begin();
			R=std::lower_bound(d[u].begin(),d[u].end(),tmpr)-d[u].begin()-1;
			if(R>=0) ans-=sd[u][R]-(L>0?sd[u][L-1]:0)+(R-L+1)*dis[x][dep[x]-dep[fa[u]]];
		}
		println(lastans=ans);
	}
	return 0;
}