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  1. #include <cstdio>
  2. #include <vector>
  3. using namespace std;
  4.  
  5. int const N = 2e5 + 10;
  6.  
  7. vector <int> e[N];
  8. bool has_p[N];
  9. int n, k;
  10. long long tot;
  11.  
  12. struct FenwickTree {
  13.     int x[N], n;
  14.     int static const OFFSET = 5;
  15.  
  16.     FenwickTree(int n=N):n(n) {}
  17.  
  18.     void add(int p, int o) {
  19.         for (p+=OFFSET; p<n; p+=p&-p) x[p] += o;
  20.     }
  21.     int sum(int p) {
  22.         int ret = 0;
  23.         for (p+=OFFSET; p>0; p-=p&-p) ret += x[p];
  24.         return ret;
  25.     }
  26. } T;
  27.  
  28. void dfs(int x) {
  29.     tot += T.sum(x+k) - T.sum(x-k-1);
  30.     T.add(x, 1);
  31.     for (int i=(int)e[x].size()-1; i>=0; --i) dfs(e[x][i]);
  32.     T.add(x, -1);
  33. }
  34.  
  35. int main() {
  36.     scanf("%d%d", &n, &k);
  37.     for (int i=1,p,c; i<n; ++i) {
  38.         scanf("%d%d", &p, &c);
  39.         e[p].push_back(c);
  40.         has_p[c] = true;
  41.     }
  42.     int root = -1;
  43.     for (root=1; root<=n&&has_p[root]; ++root);
  44.     dfs(root);
  45.     printf("%lld\n", tot);
  46.     return 0;
  47. }
  48.  
Success #stdin #stdout 0s 6780KB
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stdin 
Standard input is empty
stdout 
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https://ideone.com/QpvQwh
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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