不难的树链剖分。。。用线段树维护最大值最小值即可。。。。
#include <iostream>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <bitset>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <climits>
#include <cstdlib>
#include <cmath>
#include <time.h>
#define maxn 2000005
#define maxm 4000005
#define eps 1e-10
#define mod 1000000007
#define INF 1e9
#define lowbit(x) (x&(-x))
#define mp make_pair
#define ls o<<1
#define rs o<<1 | 1
#define lson o<<1, L, mid
#define rson o<<1 | 1, mid+1, R
//#pragma comment(linker, "/STACK:16777216")
typedef long long LL;
typedef unsigned long long ULL;
//typedef int LL;
using namespace std;
LL qpow(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base;base=base*base;b/=2;}return res;}
LL powmod(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base%mod;base=base*base%mod;b/=2;}return res;}
void scanf(int &__x){__x=0;char __ch=getchar();while(__ch==' '||__ch=='\n')__ch=getchar();while(__ch>='0'&&__ch<='9')__x=__x*10+__ch-'0',__ch = getchar();}
LL gcd(LL _a, LL _b){if(!_b) return _a;else return gcd(_b, _a%_b);}
// head
int mark[maxn << 2];
int maxv[maxn << 2];
int minv[maxn << 2];
int size[maxn];
int son[maxn];
int dep[maxn];
int top[maxn];
int fa[maxn];
int w[maxn];
char ss[maxn];
int n, z;
struct Edge
{
int v;
Edge *next;
}pool[maxm], *H[maxn], *edges;
struct node
{
int u, v, c;
node(int u = 0, int v = 0, int c = 0) : u(u), v(v), c(c) {}
}edge[maxn];
void init(void)
{
z = 0;
edges = pool;
memset(H, 0, sizeof H);
}
void addedges(int u, int v)
{
edges->v = v;
edges->next = H[u];
H[u] = edges++;
}
void read(void)
{
int u, v, c;
scanf("%d", &n);
for(int i = 1; i < n; i++) {
scanf("%d%d%d", &u, &v, &c);
edge[i] = node(u, v, c);
addedges(u, v);
addedges(v, u);
}
}
void dfs1(int u)
{
size[u] = 1, son[u] = 0;
for(Edge *e = H[u]; e; e = e->next) {
int v = e->v;
if(v != fa[u]) {
dep[v] = dep[u] + 1;
fa[v] = u;
dfs1(v);
size[u] += size[v];
if(size[son[u]] < size[v]) son[u] = v;
}
}
}
void dfs2(int u, int tp)
{
w[u] = ++z, top[u] = tp;
if(son[u]) dfs2(son[u], tp);
for(Edge *e = H[u]; e; e = e->next) {
int v = e->v;
if(v != fa[u] && v != son[u]) dfs2(v, v);
}
}
void build(int o, int L, int R)
{
maxv[o] = -INF, minv[o] = INF, mark[o] = 0;
if(L == R) return;
int mid = (L + R) >> 1;
build(lson);
build(rson);
}
void pushup(int o)
{
maxv[o] = max(maxv[ls], maxv[rs]);
minv[o] = min(minv[ls], minv[rs]);
}
void pushdown(int o)
{
if(!mark[o]) return;
swap(maxv[ls], minv[ls]);
maxv[ls] = -maxv[ls];
minv[ls] = -minv[ls];
swap(maxv[rs], minv[rs]);
maxv[rs] = -maxv[rs];
minv[rs] = -minv[rs];
mark[ls] ^= 1;
mark[rs] ^= 1;
mark[o] = 0;
}
void updata1(int o, int L, int R, int q, int v)
{
if(L == R) {
maxv[o] = minv[o] = v;
return;
}
pushdown(o);
int mid = (L + R) >> 1;
if(q <= mid) updata1(lson, q, v);
else updata1(rson, q, v);
pushup(o);
}
void updata2(int o, int L, int R, int ql, int qr)
{
if(ql <= L && qr >= R) {
mark[o] ^= 1;
swap(maxv[o], minv[o]);
maxv[o] = -maxv[o];
minv[o] = -minv[o];
return;
}
pushdown(o);
int mid = (L + R) >> 1;
if(ql <= mid) updata2(lson, ql, qr);
if(qr > mid) updata2(rson, ql, qr);
pushup(o);
}
int query(int o, int L, int R, int ql, int qr)
{
if(ql <= L && qr >= R) return maxv[o];
int mid = (L + R) >> 1, ans = -INF;
pushdown(o);
if(ql <= mid) ans = max(ans, query(lson, ql, qr));
if(qr > mid) ans = max(ans, query(rson, ql, qr));
pushup(o);
return ans;
}
void solve(int a, int b, int ok)
{
int f1 = top[a], f2 = top[b], ans = -INF;
while(f1 != f2) {
if(dep[f1] < dep[f2]) {
swap(a, b);
swap(f1, f2);
}
if(ok) updata2(1, 1, z, w[f1], w[a]);
else ans = max(ans, query(1, 1, z, w[f1], w[a]));
a = fa[f1], f1 = top[a];
}
if(a == b) {
if(!ok) printf("%d\n", ans);
return;
}
if(dep[a] > dep[b]) swap(a, b);
if(ok) updata2(1, 1, z, w[son[a]], w[b]);
else ans = max(ans, query(1, 1, z, w[son[a]], w[b]));
if(!ok) printf("%d\n", ans);
}
void work(void)
{
dfs1(1);
dfs2(1, 1);
build(1, 1, z);
for(int i = 1; i < n; i++) if(dep[edge[i].v] < dep[edge[i].u]) swap(edge[i].u, edge[i].v);
for(int i = 1; i < n; i++) updata1(1, 1, z, w[edge[i].v], edge[i].c);
int a, b;
while(scanf("%s", ss) == 1) {
if(ss[0] == 'D') break;
scanf("%d%d", &a, &b);
if(ss[0] == 'C') updata1(1, 1, z, w[edge[a].v], b);
if(ss[0] == 'Q') solve(a, b, 0);
if(ss[0] == 'N') solve(a, b, 1);
}
}
int main(void)
{
int _;
while(scanf("%d", &_)!=EOF) {
while(_--) {
init();
read();
work();
}
}
return 0;
}
