Submission #729390

#	Time	Username	Problem	Language	Result	Execution time	Memory
729390		jampm	Election Campaign (JOI15_election_campaign)	C++17	30 / 100	1057 ms	28248 KiB

election_campaign

#include <bits/stdc++.h>
using namespace std;
using ll = long long int;
const int Mxn = 1e5 + 1;
const int mxn = 2e5 + 1;


//hld
//nomás porq soy un mamador y es menos código hacer lca así que con binary lifting
int tin[Mxn], tout[Mxn], Sz[Mxn], head[Mxn], P[Mxn], Depth[Mxn], cnt = 1; 
vector<int> g[Mxn];
void get_sz(int node = 1, int parent = 1) {
  Sz[node] = 0; Depth[node] = Depth[parent] + 1; P[node] = parent;
  if (g[node][0] == parent) swap(g[node][0], g[node].back());
  for (auto & child : g[node]) {
    if (child == parent) continue;
    get_sz(child, node); Sz[node] += Sz[child];
    if (Sz[child] > Sz[g[node][0]]) swap(child, g[node][0]);
  }
}
void dfs_hld(int node = 1, int parent = 1) {
  tin[node] = cnt++;
  for (auto child : g[node]) {
    if (child == parent) continue;
    head[child] = (child == g[node][0]) ? head[node] : child;
    dfs_hld(child, node);
  }
  tout[node] = cnt++;
}
void init_hld() {head[1] = 1; Depth[1] = 0; get_sz(), dfs_hld();}
int LCA(int A, int B) {
  for (; head[A] != head[B]; A = P[head[A]]) {
    if (Depth[head[A]] < Depth[head[B]]) swap(A, B);
  }
  return (Depth[A] < Depth[B]) ? A : B;
}

//fenwi
struct fenwi {
  ll BIT[mxn];
  void upd(int i, ll val = 0) {
    for (; i < mxn; i += i&-i) BIT[i] += val;
  }
  ll sum(int i, ll val = 0) {
    for (; i > 0; i -= i&-i) val += BIT[i];
    return val;
  }
  ll query(int a, int b, int c) {
    return sum(tin[a]) + sum(tin[b]) - 2*sum(tin[c]);
  }

} bit[2];

//solve
struct query {int a, b, c;};
ll dp[Mxn], children_sum[Mxn];
vector<query> Q[Mxn];

void dfs(int node = 1, int parent = 1) {
  children_sum[node] = 0;
  for (auto child : g[node]) {
    if (child == parent) continue;
    dfs(child, node);
    children_sum[node] += dp[child];
  }
  dp[node] = children_sum[node];
  bit[0].upd(tin[node], children_sum[node]);
  bit[0].upd(tout[node], -children_sum[node]);
  for (auto [a, b, c] : Q[node]) {
    dp[node] = max(dp[node], bit[0].query(a, b, node) + children_sum[node] - bit[1].query(a, b, node) + c);
  }
  bit[1].upd(tin[node], dp[node]);
  bit[1].upd(tout[node],-dp[node]);
}


int main() {
  ios_base::sync_with_stdio(0); cin.tie(0);
  int n, m; cin >> n;
  for (int i = 1; i < n; i++) {
    int x, y; cin >> x >> y;
    g[x].push_back(y);
    g[y].push_back(x);
  }
  cin >> m; init_hld();
  for (int i = 0; i < m; i++) {
    int x, y, c; cin >> x >> y >> c;
    Q[LCA(x, y)].push_back({x, y, c});
  }
  dfs();
  cout << dp[1] << '\n';
}

• Subtask 1: 10 / 10
• Subtask 2: 5 / 5
• Subtask 3: 5 / 5
• Subtask 4: 0 / 30
• Subtask 5: 10 / 10
• Subtask 6: 0 / 40