Language: C++

#include<bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(int)n;i++)
#define all(c) (c).begin(),(c).end()
#define pb push_back
#define dbg(...) do{cerr<<__LINE__<<": ";dbgprint(#__VA_ARGS__, __VA_ARGS__);}while(0);

using namespace std;

namespace std{template<class S,class T>struct hash<pair<S,T>>{size_t operator()(const pair<S,T>&p)const{return ((size_t)1e9+7)*hash<S>()(p.first)+hash<T>()(p.second);}};template<class T>struct hash<vector<T>>{size_t operator()(const vector<T> &v)const{size_t h=0;for(auto i : v)h=h*((size_t)1e9+7)+hash<T>()(i)+1;return h;}};}
template<class T>ostream& operator<<(ostream &os, const vector<T> &v){os<<"[ ";rep(i,v.size())os<<v[i]<<(i==v.size()-1?" ]":", ");return os;}template<class T>ostream& operator<<(ostream &os,const set<T> &v){os<<"{ "; for(const auto &i:v)os<<i<<", ";return os<<"}";}
template<class T,class U>ostream& operator<<(ostream &os,const map<T,U> &v){os<<"{";for(const auto &i:v)os<<" "<<i.first<<": "<<i.second<<",";return os<<"}";}template<class T,class U>ostream& operator<<(ostream &os,const pair<T,U> &p){return os<<"("<<p.first<<", "<<p.second<<")";}
void dbgprint(const string &fmt){cerr<<endl;}template<class H,class... T>void dbgprint(const string &fmt,const H &h,const T&... r){cerr<<fmt.substr(0,fmt.find(","))<<"= "<<h<<" ";dbgprint(fmt.substr(fmt.find(",")+1),r...);}
typedef long long ll;typedef vector<int> vi;typedef pair<int,int> pi;const int inf = (int)1e9;const double INF = 1e12, EPS = 1e-9;
const int MX = 100000;
const int MX_L=17;

int n, K;
int parent[MX_L][MX];
int depth[MX];
vector<vector<pi>> e;

void dfs(int c, int p, int d){
	depth[c] = d;
	parent[0][c] = p;
	for(pi i : e[c]){
		int to = i.first;
		if(to == p) continue;
		dfs(to, c, d + 1);
	}
}
inline int lca(int a, int b){
	if(depth[a] > depth[b]) swap(a, b);
	int d = depth[b] - depth[a];
	rep(i, MX_L) if(d & 1 << i) b = parent[i][b];
	if(a == b) return a;
	for(int i = MX_L - 1; i >= 0; i--) if(parent[i][a] != parent[i][b]){
		a = parent[i][a];
		b = parent[i][b];
	}
	return parent[0][a];
}

vector<pi> tmpq; //pos, add
ll cost_sum[MX], edge_sum[MX], added[MX];
void build(){
	for(pi i : tmpq) added[i.first] += i.second;
	tmpq.clear();
	function<void(int,int,ll,ll)> rec = [&](int c, int p, ll cs, ll es){
		cost_sum[c] = cs;
		edge_sum[c] = es;
		for(pi i : e[c]) if(i.first != p){
			ll ec = added[c] + added[i.first] + i.second;
			ll x = cs + (ec % K ? ec : 0);
			ll y = es + ec;
			rec(i.first, c, x, y);
		}
	};
	rec(0, 0, 0, 0);
}
ll cost(int a, int b){ return cost_sum[a] - cost_sum[b]; }
ll cost(int a, int b, unordered_map<int,int> &m){
	ll ec = edge_sum[a] - edge_sum[b];
	if(m.count(a)) ec += m[a];
	if(m.count(b)) ec += m[b];
	return ec % K ? ec : 0;
}
ll calc(int s, int t){
	if(s == t) return 0;
	ll ans = cost_sum[s] - cost_sum[t];
	unordered_map<int,int> tmpadd;
	for(pi i : tmpq) if(lca(s, i.first) == i.first) tmpadd[i.first] += i.second;
	for(pi i : tmpadd){
		int prev = s, next = parent[0][i.first], diff = max(0, depth[s] - depth[i.first] - 1);
		rep(j, MX_L) if(diff >> j & 1) p1rev = parent[j][prev];
		if(i.first != s) ans -= cost(prev, i.first) - cost(prev, i.first, tmpadd);
		if(i.first != t) ans -= cost(i.first, next) - cost(i.first, next, tmpadd);
	}
	return ans;
}
int query(int s, int t){
	int m = lca(s, t);
	return calc(s, m) + calc(t, m);
}
int main(){
	cin.tie(0); cin.sync_with_stdio(0);
	cin >> n >> K;
	e.resize(n);
	rep(i, n - 1){
		int a, b, c;
		cin >> a >> b >> c;
		e[a].emplace_back(b, c);
		e[b].emplace_back(a, c);
	}
	dfs(0, 0, 0);
	rep(i, MX_L - 1) rep(j, n) parent[i + 1][j] = parent[i][parent[i][j]];
	build();
	
	int Q; cin >> Q;
	const int B = 500;
	rep(i, Q){
		string s; int a, b; cin >> s >> a >> b;
		if(s[0] == 'a'){
			tmpq.emplace_back(a, b);
			if(tmpq.size() == B) build();
		}
		else cout << query(a, b) << endl;
	}
	
	return 0;
}


Compiler output:
a.cc: In function 'll calc(int, int)':
a.cc:74:48: error: 'p1rev' was not declared in this scope; did you mean 'prev'?
   74 |                 rep(j, MX_L) if(diff >> j & 1) p1rev = parent[j][prev];
      |                                                ^~~~~
      |                                                prev