fork(4) download 
  1. var
  2.   i, j, k, n, d, u, v: longint;
  3.   c: int64;
  4.   a: array[1..5000, 1..5000] of longint;
  5.  
  6. function min(a, b: longint): longint;
  7. begin
  8.   if a > b then a := b;
  9.   min := a;
  10. end;
  11.  
  12.  
  13. begin{
  14. assign(input, 'capitals.in'); reset(input);
  15. assign(output, 'capitals.out'); rewrite(output);}
  16.   read(n, d);
  17.   for i := 1 to n do
  18.     for j := 1 to n do a[i][j] := 1000000000;
  19.  
  20.   for i := 1 to n - 1 do
  21.   begin
  22.     read(u, v);
  23.     a[u][v] := 1;
  24.     a[v][u] := 1;
  25.   end;
  26.  
  27.   for k := 1 to n do
  28.     for i := 1 to n do
  29.       for j := 1 to n do
  30.         if i<>j then a[i][j] := min(a[i][j], a[i][k] + a[k][j]);
  31.   {
  32.   for i := 1 to n do
  33.   begin
  34.     for j := 1 to n do write(a[i][j], ' ');
  35.     writeln;
  36.   end;      }
  37.   for k := 1 to n do
  38.     for i := 1 to n do
  39.       for j := 1 to n do 
  40.         if (a[i][j] = d) and (a[i][k] = d) and  (a[j][k] = d) then inc(c);
  41.   writeln(c / 6);
  42.  
  43. end.
Success #stdin #stdout 0.02s 97920KB
comments (?)
stdin 
5 2
1 4
3 4
5 2
5 4
stdout 
 1.0000000000000000E+0000
https://ideone.com/HramHv
language:
Pascal (fpc 3.0.4)
created:
11 years ago
visibility:
secret

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