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  1. #include <bits/stdc++.h>
  2.  
  3. using namespace std;
  4.  
  5. #define ll int
  6. #define pll pair < int, int >
  7.   #define debug(x) 0
  8.  
  9. // 1 indexing
  10. struct LCA {
  11.   ll LOG, n;
  12.   vector < vector < pll >> adj;
  13.   vector < vector < ll >> btree;
  14.   vector < ll > depth;
  15.  
  16.   LCA(ll _n, vector < vector < pll >> & _adj) // no of nodes
  17.   {
  18.     n = _n;
  19.     LOG = log2(n) + 1;
  20.     btree.resize(n + 1, vector < ll > (LOG));
  21.     adj = _adj;
  22.     depth.resize(n + 1, 0);
  23.   }
  24.  
  25.   void make_tree(ll a, ll prv = -1) {
  26.     for (auto[b, w]: adj[a]) {
  27.       if (b == prv) continue;
  28.  
  29.       depth[b] = depth[a] + 1;
  30.       btree[b][0] = a; // a is parent of b
  31.       for (int j = 1; j < LOG; j++) btree[b][j] = btree[btree[b][j - 1]][j - 1];
  32.       make_tree(b, a);
  33.     }
  34.   }
  35.  
  36.   ll find_lca(ll u, ll v) {
  37.     if (depth[u] < depth[v]) swap(u, v);
  38.     int k = depth[u] - depth[v];
  39.     for (int i = LOG - 1; i >= 0; i--) {
  40.       if (k & (1 << i)) u = btree[u][i];
  41.     }
  42.     if (u == v) return u;
  43.     for (int i = LOG - 1; i >= 0; i--) {
  44.       if (btree[u][i] != btree[v][i]) {
  45.         u = btree[u][i];
  46.         v = btree[v][i];
  47.       }
  48.     }
  49.     return btree[u][0];
  50.   }
  51. };
  52.  
  53. void get_sum(int curr, int prv, vector < int > & ans, vector < vector < pll >> & adj, vector < vector < ll >> & psum) {
  54.   psum[curr] = ans;
  55.   for (auto[x, w]: adj[curr]) {
  56.     if (x == prv) continue;
  57.     ans[w]++;
  58.     get_sum(x, curr, ans, adj, psum);
  59.     ans[w]--;
  60.   }
  61. }
  62.  
  63. vector < int > solve(int n, vector < vector < pll >> & adj, int q, vector < vector < int >> & queries) {
  64.  
  65.   vector < vector < ll >> psum(n + 1, vector < ll > (27, 0));
  66.   LCA lc(n, adj);
  67.   lc.make_tree(1);
  68.  
  69.   vector < ll > f_arr(27, 0);
  70.   get_sum(1, 0, f_arr, adj, psum);
  71.  
  72.   debug(psum[1]);
  73.  
  74.   vector < int > res;
  75.   res.reserve(q);
  76.   for (int qq = 0; qq < q; qq++) {
  77.     int a = queries[qq][0];
  78.     int b = queries[qq][1];
  79.  
  80.     int par = lc.find_lca(a, b), tot = 0, cnt = 0, val = 0;
  81.     fill(f_arr.begin(), f_arr.end(), 0);
  82.  
  83.     for (int i = 0; i < 27; i++) {
  84.       f_arr[i] += (psum[a][i] + psum[b][i]) - 2 * psum[par][i];
  85.       tot += f_arr[i];
  86.     }
  87.     cnt = (tot + 1) / 2;
  88.     tot = 0;
  89.     for (int i = 0; i < 27; i++) {
  90.       tot += f_arr[i];
  91.       if (tot >= cnt) {
  92.         cnt = i;
  93.         break;
  94.       }
  95.     }
  96.     int ans = 0;
  97.  
  98.     for (int i = 0; i < 27; i++) {
  99.       ans += f_arr[i] * abs(i - cnt);
  100.     }
  101.     res.push_back(ans);
  102.   }
  103.   return res;
  104. }
  105.  
  106. int main() {
  107.  
  108.   ios::sync_with_stdio(0);
  109.   cin.tie(0);
  110.   int n;
  111.   cin >> n;
  112.   vector < vector < int > > edges(n - 1, vector < int > (3));
  113.   for (int i_edges = 0; i_edges < n - 1; i_edges++) {
  114.     for (int j_edges = 0; j_edges < 3; j_edges++) {
  115.       cin >> edges[i_edges][j_edges];
  116.     }
  117.   }
  118.  
  119.   vector < vector < pll >> adj(n + 1);
  120.   for (int i = 0; i < n - 1; i++) {
  121.     int u, v, w;
  122.     u = edges[i][0];
  123.     v = edges[i][1];
  124.     w = edges[i][2];
  125.     adj[u].push_back({
  126.       v,
  127.       w
  128.     });
  129.     adj[v].push_back({
  130.       u,
  131.       w
  132.     });
  133.   }
  134.  
  135.   int Q;
  136.   cin >> Q;
  137.   vector < vector < int > > Queries(Q, vector < int > (2));
  138.   for (int i_Queries = 0; i_Queries < Q; i_Queries++) {
  139.     for (int j_Queries = 0; j_Queries < 2; j_Queries++) {
  140.       cin >> Queries[i_Queries][j_Queries];
  141.     }
  142.   }
  143.  
  144.   vector < int > out_;
  145.   out_ = solve(n, adj, Q, Queries);
  146.   cout << out_[0];
  147.   for (int i_out_ = 1; i_out_ < out_.size(); i_out_++) {
  148.     cout << " " << out_[i_out_];
  149.   }
  150. }
Success #stdin #stdout 0.01s 5360KB
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https://ideone.com/X2rjq1
language:
C++14 (gcc 8.3)
created:
1 year ago
visibility:
secret

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