#include <bits/stdc++.h>
#define ll long long
#define task "GRAPEVINE"
using namespace std;
const int N = 1e5 + 16;
const ll INF = 1e18;
int n, q, u, v;
ll w;
vector < pair <int, ll> > adj[N];
namespace sub6 {
int h[N], up[N][26], timeDfs, in[N], out[N];
ll d[N], val[N];
void dfs(int k) {
timeDfs++;
in[k] = timeDfs;
for (auto v : adj[k]) {
if (v.first == up[k][0]) {
continue;
}
d[v.first] = d[k] + v.second;
val[v.first] = v.second;
h[v.first] = h[k] + 1;
up[v.first][0] = k;
for (int i = 1; i <= 20; i++) {
up[v.first][i] = up[up[v.first][i - 1]][i - 1];
}
dfs(v.first);
}
out[k] = timeDfs;
}
int lca(int u, int v) {
if (h[u] != h[v]) {
if (h[u] < h[v]) {
swap(u, v);
}
int k = h[u] - h[v];
for (int i = 0; (1 << i) <= k; i++) {
if (k >> i & 1) {
u = up[u][i];
}
}
}
if (u == v) {
return u;
}
int k = __lg(h[u]);
for (int i = k; i >= 0; i--) {
if (up[u][i] != up[v][i]) {
u = up[u][i];
v = up[v][i];
}
}
return up[u][0];
}
bool checkSubtree(int root, int k) {
return in[root] <= in[k] && out[k] <= out[root];
}
bool cmp(int a, int b) {
return in[a] < in[b];
}
int sz[N], parCd[N];
bool visited[N];
void countChild(int k, int p) {
sz[k] = 1;
for (auto v : adj[k]) {
if (v.first == p || visited[v.first]) {
continue;
}
countChild(v.first, k);
sz[k] += sz[v.first];
}
}
int findCentroid(int k, int p, int treeSz) {
for (auto v : adj[k]) {
if (v.first == p || visited[v.first]) {
continue;
}
if (sz[v.first] > (treeSz >> 1)) {
return findCentroid(v.first, k, treeSz);
}
}
return k;
}
int cd(int k) {
countChild(k, k);
int centroid = findCentroid(k, k, sz[k]);
visited[centroid] = true;
for (auto v : adj[centroid]) {
if (!visited[v.first]) {
parCd[cd(v.first)] = centroid;
}
}
return centroid;
}
struct node {
ll d = INF, answer = INF;
int state = 0;
ll lazy = 0;
node operator + (const node &other) const {
node ans;
if (answer < other.answer) {
ans.d = d;
ans.answer = answer;
ans.state = state;
}
else {
ans.d = other.d;
ans.answer = other.answer;
ans.state = other.state;
}
return ans;
}
};
struct IT {
int n, root;
vector <int> lst;
vector <node> segmentTree;
void build(int k, int l, int r) {
if (l == r) {
segmentTree[k].d = d[lst[l - 1]] + d[root] - 2 * d[lca(lst[l - 1], root)];
return;
}
int mid = l + r >> 1;
build(k << 1, l, mid);
build(k << 1 | 1, mid + 1, r);
}
void down(int k) {
ll t = segmentTree[k].lazy;
if (t == 0) {
return;
}
segmentTree[k << 1].d += t;
segmentTree[k << 1].answer += t;
segmentTree[k << 1].answer = min(segmentTree[k << 1].answer, INF);
segmentTree[k << 1].lazy += t;
segmentTree[k << 1 | 1].d += t;
segmentTree[k << 1 | 1].answer += t;
segmentTree[k << 1 | 1].answer = min(segmentTree[k << 1 | 1].answer, INF);
segmentTree[k << 1 | 1].lazy += t;
segmentTree[k].lazy = 0;
}
void updateRange(int k, int l, int r, int x, int y, ll w) {
if (l > y || x > r) {
return;
}
if (l >= x && r <= y) {
segmentTree[k].d += w;
segmentTree[k].answer += w;
segmentTree[k].answer = min(segmentTree[k].answer, INF);
segmentTree[k].lazy += w;
return;
}
int mid = l + r >> 1;
down(k);
updateRange(k << 1, l, mid, x, y, w);
updateRange(k << 1 | 1, mid + 1, r, x, y, w);
segmentTree[k] = segmentTree[k << 1] + segmentTree[k << 1 | 1];
}
void updatePoint(int k, int l, int r, int x) {
if (l > x || x > r) {
return;
}
if (l == r) {
segmentTree[k].state ^= 1;
if (segmentTree[k].state) {
segmentTree[k].answer = segmentTree[k].d;
}
else {
segmentTree[k].answer = INF;
}
return;
}
int mid = l + r >> 1;
down(k);
updatePoint(k << 1, l, mid, x);
updatePoint(k << 1 | 1, mid + 1, r, x);
segmentTree[k] = segmentTree[k << 1] + segmentTree[k << 1 | 1];
}
ll get(int k, int l, int r, int x) {
if (l == r) {
return segmentTree[k].d;
}
int mid = l + r >> 1;
down(k);
if (x <= mid) {
return get(k << 1, l, mid, x);
}
return get(k << 1 | 1, mid + 1, r, x);
}
};
IT tree[N];
int lowerBound(vector <int> &lst, int pos) {
int l = 0, r = lst.size() - 1, mid, res = lst.size();
while (l <= r) {
mid = l + r >> 1;
if (in[lst[mid]] >= pos) {
r = mid - 1;
res = mid;
}
else {
l = mid + 1;
}
}
res++;
return res;
}
int upperBound(vector <int> &lst, int pos) {
int l = 0, r = lst.size() - 1, mid, res = lst.size();
while (l <= r) {
mid = l + r >> 1;
if (in[lst[mid]] > pos) {
r = mid - 1;
res = mid;
}
else {
l = mid + 1;
}
}
res++;
return res;
}
ll query(int u) {
ll ans = INF;
int cur = u;
while (cur) {
int p = lowerBound(tree[cur].lst, in[u]);
ans = min(ans, tree[cur].get(1, 1, tree[cur].n, p) + tree[cur].segmentTree[1].answer);
cur = parCd[cur];
}
if (ans == INF) {
ans = -1;
}
return ans;
}
void change(int u) {
int cur = u;
while (cur) {
int p = lowerBound(tree[cur].lst, in[u]);
tree[cur].updatePoint(1, 1, tree[cur].n, p);
cur = parCd[cur];
}
}
void path(int u, ll w) {
int cur = u;
while (cur) {
int L = lowerBound(tree[cur].lst, in[u]);
int R = upperBound(tree[cur].lst, out[u]);
R--;
if (L <= R && R <= tree[cur].n) {
if (checkSubtree(u, cur)) {
if (L - 1 >= 1) {
tree[cur].updateRange(1, 1, tree[cur].n, 1, L - 1, w);
}
if (R + 1 <= tree[cur].n) {
tree[cur].updateRange(1, 1, tree[cur].n, R + 1, tree[cur].n, w);
}
}
else {
tree[cur].updateRange(1, 1, tree[cur].n, L, R, w);
}
}
cur = parCd[cur];
}
}
void solve() {
dfs(1);
cd(1);
for (int i = 1; i <= n; i++) {
u = i;
while (u) {
tree[u].lst.push_back(i);
u = parCd[u];
}
}
for (int i = 1; i <= n; i++) {
sort(tree[i].lst.begin(), tree[i].lst.end(), cmp);
}
for (int i = 1; i <= n; i++) {
tree[i].n = tree[i].lst.size();
tree[i].root = i;
node defVal;
tree[i].segmentTree.resize((tree[i].n + 1) << 2, defVal);
tree[i].build(1, 1, tree[i].n);
}
while (q--) {
int type, u;
cin >> type >> u;
if (type == 1) {
cout << query(u) << "\n";
}
else if (type == 2) {
change(u);
}
else {
cin >> v >> w;
int p = h[u] < h[v] ? v : u;
path(p, w - val[p]);
val[p] = w;
}
}
}
}
int main() {
ios_base :: sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
if (fopen(task".inp", "r")) {
freopen(task".inp", "r", stdin);
freopen(task".out", "w", stdout);
}
cin >> n >> q;
for (int i = 1; i < n; i++) {
cin >> u >> v >> w;
adj[u].push_back({v, w});
adj[v].push_back({u, w});
}
sub6 :: solve();
return 0;
}
컴파일 시 표준 에러 (stderr) 메시지
Main.cpp: In function 'int main()':
Main.cpp:340:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
340 | freopen(task".inp", "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:341:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
341 | freopen(task".out", "w", stdout);
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