0pts过样例求调，（悬6关）

#include<bits/stdc++.h>
using namespace std;
#define int long long
const int N=1e5;
struct node
{
    int nxt,id,w;
};
struct segtree
{
    int l,r;
    int chtag,adtag;
    int maxx;
}tree[4*N+5];
int n;
int a[N+5];
int s[N+5];
int fa[N+5],dep[N+5],siz[N+5],son[N+5];
int dfncnt,dfn[N+5],seg[N+5],tp[N+5];
vector<node>to[N+5];
void dfs1(int anc,int root)
{
    int maxx=0;
    fa[root]=anc;
    dep[root]=dep[anc]+1;
    siz[root]=1;
    for(auto v:to[root])
    {
        if(v.nxt==anc) continue;
        s[v.id]=v.nxt;   //第v.id条边的权值在v.nxt（儿子）上 
        a[v.nxt]=v.w;    //边权转点权 
        dfs1(root,v.nxt);
        siz[root]+=siz[v.nxt];
        if(siz[v.nxt]>maxx)
        {
            maxx=siz[v.nxt];
            son[root]=v.nxt;
        }
    }
    return ;
}
void dfs2(int root,int topp)
{
    tp[root]=topp;
    dfn[root]=++dfncnt;
    seg[dfncnt]=root;
    if(!son[root]) return ;
    dfs2(son[root],topp);
    for(auto v:to[root])
    {
        if(v.nxt==fa[root] || v.nxt==son[root]) continue;
        dfs2(v.nxt,v.nxt);
    }
    return ;
}
void build(int k,int l,int r)
{
    tree[k].l=l,tree[k].r=r;
    if(l==r)
    {
    	tree[k].maxx=a[seg[l]];
    	return ;
	}
    int mid=(l+r)>>1;
    build(k<<1,l,mid);
    build(k<<1|1,mid+1,r);
    tree[k].maxx=max(tree[k<<1].maxx,tree[k<<1|1].maxx); 
    return ;
}
void push_down(int k)
{
    if(tree[k].chtag!=-1)
    {
        int tag=tree[k].chtag;
        tree[k].chtag=-1;
        tree[k<<1].chtag=tag;
        tree[k<<1|1].chtag=tag;
        tree[k<<1].maxx=tag;
        tree[k<<1|1].maxx=tag;
    }
    int tag=tree[k].adtag;
    tree[k].adtag=0;
    tree[k<<1].adtag+=tag;
    tree[k<<1|1].adtag+=tag;
    tree[k<<1].maxx+=tag;
    tree[k<<1|1].maxx+=tag;
    return ;
}
void change(int k,int l,int r,int x)
{
    if(tree[k].l>=l && tree[k].r<=r)
    {
        tree[k].chtag=x;
        tree[k].adtag=0;
        tree[k].maxx=x;
        return ;
    }
    push_down(k);
    int mid=(tree[k].l+tree[k].r)>>1;
    if(mid>=l)
        change(k<<1,l,r,x);
    if(mid+1<=r)
        change(k<<1|1,l,r,x);
    tree[k].maxx=max(tree[k<<1].maxx,tree[k<<1|1].maxx);
    return;
}
void add(int k,int l,int r,int x)
{
//	cout<<k<<" "<<tree[k].l<<" "<<tree[k].r<<"\n";
    if(tree[k].l>=l && tree[k].r<=r)
    {
        tree[k].maxx+=x;
        tree[k].adtag+=x;
        return ;
    }
    push_down(k);
    int mid=(tree[k].l+tree[k].r)>>1;
    if(mid>=l)
        add(k<<1,l,r,x);
    if(mid+1<=r)
        add(k<<1|1,l,r,x);
    tree[k].maxx=max(tree[k<<1].maxx,tree[k<<1|1].maxx);
    return ;
}
int ask(int k,int l,int r)
{
//	cout<<tree[k].l<<" "<<tree[k].r<<"\n";
    int maxx=0;
    if(tree[k].l>=l && tree[k].r<=r)
        return tree[k].maxx;
    int mid=(tree[k].l+tree[k].r)>>1;
    if(mid>=l)
        maxx=max(maxx,ask(k<<1,l,r));
    if(mid+1<=r)
        maxx=max(maxx,ask(k<<1|1,l,r));
    return maxx;
}
int ask_path(int xx,int yy)
{
    int ans=0;
    int x=xx,y=yy;
    while(tp[x]!=tp[y])
    {
//    	cout<<x<<" "<<y<<"\n";
        if(dep[tp[x]]<dep[tp[y]])
            swap(x,y);
        ans=max(ans,ask(1,dfn[tp[x]],dfn[x]));
        x=fa[tp[x]];
    }
    if(dep[x]>dep[y])
        swap(x,y);
    ans=max(ans,ask(1,dfn[x]+1,dfn[y]));
    return ans;
}
void change_path(int xx,int yy,int cg)
{
    int ans=0;
    int x=xx,y=yy;
    while(tp[x]!=tp[y])
    {
        if(dep[tp[x]]<dep[tp[y]])
            swap(x,y);
        change(1,dfn[tp[x]],dfn[x],cg);
        x=fa[tp[x]];
    }
    if(dep[x]>dep[y])
        swap(x,y);
    change(1,dfn[x]+1,dfn[y],cg);
    return ;
}
void add_path(int xx,int yy,int cg)
{
    int ans=0;
    int x=xx,y=yy;
    while(tp[x]!=tp[y])
    {
//    	cout<<x<<" "<<y<<"\n";
        if(dep[tp[x]]<dep[tp[y]])
            swap(x,y);
        add(1,dfn[tp[x]],dfn[x],cg);
        x=fa[tp[x]];
    }
    if(dep[x]>dep[y])
        swap(x,y);
    add(1,dfn[x]+1,dfn[y],cg);
    return ;
}
main()
{
    cin>>n;
    for(int i=1;i<=n-1;i++)
    {
        int u,v,w;
        cin>>u>>v>>w;
        to[u].push_back({v,i,w}),to[v].push_back({u,i,w});
    }
    dfs1(1,1);
    dfs2(1,1);
    build(1,1,n);
    while(true)
    {
        int x,y,z;
        string op;
        cin>>op;
//        cout<<op<<"\n";
        if(op[0]=='S') break;
        if(op[0]=='M')
        {
//        	cout<<"jkfsdjkfsdjklfjksdl\n";
            cin>>x>>y;
            cout<<ask_path(x,y)<<"\n";
        }
        else if(op=="Cover")
        {
            cin>>x>>y>>z;
            change_path(x,y,z);
        }
        else if(op=="Change")
        {
            cin>>x>>y;
            change(1,dfn[s[x]],dfn[s[x]],y);
        }
        else
        {
//        	cout<<"fjfjfjjfdjfdj\n";
            cin>>x>>y>>z;
            add_path(x,y,z);
        }
    }
    return 0;
}