链接:lg2420[边权]
题解
- 和维护点权差不多,脑洞yy一下
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using namespace std;
const int N=1e6;
ll rt[N],lz[N],deep[N],size[N],hson[N],f[N],top[N],id[N];
ll head[N],nxt[N],to[N],w[N],wt[N],wc[N];
int cnt,n,m;
inline void adde(int u,int v,int x){nxt[++cnt]=head[u];to[cnt]=v;wt[cnt]=x;head[u]=cnt;}
inline void pushup(int o){rt[o]=rt[o<<1]^rt[o<<1|1];}
inline void build(int o,int l,int r){
if(l==r){rt[o]=w[l];return ;}
int mid=l+r>>1;
build(lson);
build(rson);
pushup(o);
}
inline ll query(int o,int l,int r,int L,int R){
if(L<=l&&R>=r)return rt[o];
int mid=l+r>>1;
ll ans=0;
if(L<=mid){ll tp=query(lson,L,R);if(!ans)ans=tp;else ans^=tp;}
if(R>mid){ll tp=query(rson,L,R);if(!ans)ans=tp;else ans^=tp;}
return ans;
}
inline void dfs1(int x){
size[x]=1;
for(int i=head[x];i;i=nxt[i])if(to[i]!=f[x]){
wc[to[i]]=wt[i];
f[to[i]]=x;
deep[to[i]]=deep[x]+1;
dfs1(to[i]);
size[x]+=size[to[i]];
if(size[hson[x]]<size[to[i]])hson[x]=to[i];
}
}
inline void dfs2(int x,int t){
top[x]=t;id[x]=++cnt;w[cnt]=wc[x];
if(hson[x])dfs2(hson[x],t);
for(int i=head[x];i;i=nxt[i])if(to[i]!=hson[x]&&to[i]!=f[x])dfs2(to[i],to[i]);
}
inline ll queryrange(int x,int y){
ll ans=0;
while(top[x]!=top[y]){
if(deep[top[x]]<deep[top[y]])swap(x,y);
ll tp=query(1,1,n,id[top[x]],id[x]);
if(!ans)ans=tp;else ans^=tp;
x=f[top[x]];
}
if(x==y)return ans;
if(deep[x]>deep[y])swap(x,y);
return ans^query(1,1,n,id[hson[x]],id[y]);
}
int main(){
scanf("%d",&n);
rep(i,2,n){
int x,y,z;
scanf("%d%d%d",&x,&y,&z);
adde(x,y,z);adde(y,x,z);
}cnt=0;
dfs1(1);
dfs2(1,1);
build(1,1,n);
scanf("%d",&m);
while(m--){
int x,y;
scanf("%d%d",&x,&y);
printf("%lld\n",queryrange(x,y));
}
return 0;
}