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  1. #include <algorithm>  // max_element
  2. #include <functional> // function
  3. #include <iostream>
  4. #include <iterator>   // istream_iterator
  5. #include <vector>
  6.  
  7. int main()
  8. {
  9.   // get the number of nodes
  10.   size_t n;
  11.   if (!(std::cin >> n))
  12.     return 1;
  13.  
  14.   // read nodes from stdin
  15.   std::istream_iterator<int> nodes{std::cin}, eof;
  16.   std::vector<int> a(nodes, eof); // a[i] is the parent of an i node, -1 is root
  17.   if (a.size() != n)
  18.     return 2;
  19.  
  20.   // find all depths for each i node
  21.   std::vector<int> d(n); // d[i] -- depth of i node
  22.   std::function<int(size_t)> depth = [&](size_t i) -> int {
  23.     if (!d[i])
  24.       d[i] = (a[i] == -1) ? 1 : 1 + depth(a[i] - 1);
  25.     return d[i];
  26.   };
  27.   for (size_t i = 0; i < n; ++i)
  28.     depth(i);
  29.  
  30.   // find max depth
  31.   auto it = std::max_element(std::begin(d), std::end(d));
  32.   std::cout << ((it == std::end(d)) ? 0 : *it);
  33. }
Success #stdin #stdout 0s 16064KB
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stdin
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5
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stdout
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3
https://ideone.com/B1ONFE
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
secret

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