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| #include <bits/stdc++.h>
using namespace std;
#define FO(x) freopen(#x".in","r",stdin),freopen(#x".out","w",stdout)
#define fo(i,j,k) for(int i=(j),end_i=(k);i<=end_i;i++)
#define ff(i,j,k) for(int i=(j),end_i=(k);i< end_i;i++)
#define fd(i,j,k) for(int i=(j),end_i=(k);i>=end_i;i--)
#define DEBUG(x) cerr<<#x<<"="<<x<<endl
#define all(x) (x).begin(),(x).end()
#define cle(x) memset(x,0,sizeof(x))
#define lowbit(x) ((x)&-(x))
#define ll long long
#define ull unsigned ll
#define db double
#define lb long db
#define pb push_back
#define mp make_pair
#define fi first
#define se second
inline int read()
{
int x=0; char ch=getchar(); bool f=0;
for(;ch<'0'||ch>'9';ch=getchar()) if(ch=='-') f=1;
for(;ch>='0'&&ch<='9';ch=getchar()) x=(x<<3)+(x<<1)+(ch^48);
return f?-x:x;
}
#define CASET fo(___,1,read())
const int N=5e5+5;
const ll inf=1ll<<60;
namespace SGT{
#define lc (u<<1)
#define rc (u<<1|1)
#define ls lc,l,mid
#define rs rc,mid+1,r
ll mx[N<<2],tag[N<<2];
inline void pushtag(int u,ll x)
{
mx[u]+=x; tag[u]+=x;
}
inline void pushdown(int u)
{
if(!tag[u]) return;
pushtag(lc,tag[u]);
pushtag(rc,tag[u]);
tag[u]=0;
}
inline void pushup(int u)
{
mx[u]=min(mx[lc],mx[rc]);
}
void add(int u,int l,int r,int L,int R,ll v)
{
if(L<=l&&r<=R) return pushtag(u,v);
int mid=l+r>>1;
pushdown(u);
if(L<=mid) add(ls,L,R,v);
if(mid<R) add(rs,L,R,v);
pushup(u);
}
ll ask(int u,int l,int r,int L,int R)
{
if(L<=l&&r<=R) return mx[u];
pushdown(u);
int mid=l+r>>1;
ll ans=inf;
if(L<=mid) ans=min(ans,ask(ls,L,R));
if(mid<R) ans=min(ans,ask(rs,L,R));
return ans;
}
void ins(int u,int l,int r,int p,ll v)
{
if(l==r) return (void)(mx[u]=v);
int mid=l+r>>1;
(p<=mid)?ins(ls,p,v):ins(rs,p,v);
pushup(u);
}
}
struct query{
int l,r,id;
};
vector<query> q[N];
vector<int> leaf;
int n,m,fa[N];
ll ans[N],now;
int ver[N],val[N],ne[N],head[N],tot=1;
inline void add(int x,int y,int z)
{
ver[++tot]=y; val[tot]=z; ne[tot]=head[x]; head[x]=tot;
}
int le[N],ri[N];
void dfs(int u)
{
for(auto x:q[u])
ans[x.id]=SGT::ask(1,1,n,x.l,x.r)+now;
for(int i=head[u],v;i;i=ne[i])
{
v=ver[i];
now+=val[i];
SGT::add(1,1,n,le[v],ri[v],-val[i]*2);
dfs(v);
now-=val[i];
SGT::add(1,1,n,le[v],ri[v],val[i]*2);
}
}
void pre(int u,ll now)
{
le[u]=n+1,ri[u]=0;
for(int i=head[u],v;i;i=ne[i])
{
v=ver[i];
pre(v,now+val[i]);
le[u]=min(le[u],le[v]);
ri[u]=max(ri[u],ri[v]);
}
if(!head[u]) le[u]=ri[u]=u,SGT::ins(1,1,n,u,now);
else SGT::ins(1,1,n,u,inf);
}
int main()
{
n=read(); m=read();
fo(i,2,n)
{
fa[i]=read();
add(fa[i],i,read());
}
fo(i,1,n) if(!head[i]) leaf.pb(i);
pre(1,0);
int v,l,r;
fo(i,1,m)
{
v=read(); l=read(); r=read();
l=lower_bound(all(leaf),l)-leaf.begin();
r=upper_bound(all(leaf),r)-leaf.begin()-1;
if(l>r) continue;
q[v].pb((query){leaf[l],leaf[r],i});
}
dfs(1);
fo(i,1,m) printf("%lld\n",ans[i]);
return 0;
}
|
