Language: C++


#include<bits/stdc++.h>
using namespace std;
double prob(double a, double b, double c, double n, vector<vector<vector<double>>> &dp) {
	double ret{};
	if (a > 0) {
		//	ret += prob(a - 1, b, c) * transition of (a, b, c) to (a - 1, b, c)
		ret += prob(a - 1, b, c, n, dp) * (a / n);
	}
	if (b > 0) {
		//	ret += prob(a + 1, b - 1, c) * transition of (a, b, c) to (a + 1, b - 1, c)
		ret += prob(a + 1, b - 1, c, n, dp) * (b / n);
	}

	if (c > 0) {
		//	ret += prob(a, b + 1, c - 1) * transition of (a, b, c) to (a, b + 1, c - 1)
		ret += prob(a, b + 1, c - 1, n, dp) * (c / n);
	}
	if (a == 0 && b == 0 && c == 0) {
		return 1;
	}
	return dp[a][b][c] = ret;
}
int main() {
	double n;
	cin >> n;
	vector<int> v(n);
	double aa{}, bb{}, cc{};
	for (int i{}; i < n; i++) {
		cin >> v[i];
		if (v[i] == 1)aa++;
		else if (v[i] == 2)bb++;
		else cc++;
	}
	vector<vector<vector<double>>> dp (aa + 1, vector < vector<double>(bb + 1, vector<double>(cc + 1)));
//	double dp[a + 1][b + 1][c + 1] {};
	return 1 / prob(aa, bb, cc, n, dp);
}

Compiler output:
a.cc: In function 'int main()':
a.cc:35:106: error: no matching function for call to 'std::vector<double>::vector(double, std::vector<double>)'
   35 |         vector<vector<vector<double>>> dp (aa + 1, vector < vector<double>(bb + 1, vector<double>(cc + 1)));
      |                                                                                                          ^
In file included from /usr/include/c++/14/vector:66,
                 from /usr/include/c++/14/functional:64,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:53,
                 from a.cc:2:
/usr/include/c++/14/bits/stl_vector.h:707:9: note: candidate: 'template<class _InputIterator, class> std::vector<_Tp, _Alloc>::vector(_InputIterator, _InputIterator, const allocator_type&) [with <template-parameter-2-2> = _InputIterator; _Tp = double; _Alloc = std::allocator<double>]'
  707 |         vector(_InputIterator __first, _InputIterator __last,
      |         ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:707:9: note:   template argument deduction/substitution failed:
a.cc:35:106: note:   deduced conflicting types for parameter '_InputIterator' ('double' and 'std::vector<double>')
   35 |         vector<vector<vector<double>>> dp (aa + 1, vector < vector<double>(bb + 1, vector<double>(cc + 1)));
      |                                                                                                          ^
/usr/include/c++/14/bits/stl_vector.h:678:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::initializer_list<_Tp>, const allocator_type&) [with _Tp = double; _Alloc = std::allocator<double>; allocator_type = std::allocator<double>]'
  678 |       vector(initializer_list<value_type> __l,
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:678:43: note:   no known conversion for argument 1 from 'double' to 'std::initializer_list<double>'
  678 |       vector(initializer_list<value_type> __l,
      |              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/stl_vector.h:659:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::vector<_Tp, _Alloc>&&, std::__type_identity_t<_Alloc>&) [with _Tp = double; _Alloc = std::allocator<double>; std::__type_identity_t<_Alloc> = std::allocator<double>]'
  659 |       vector(vector&& __rv, const __type_identity_t<allocator_type>& __m)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:659:23: note:   no known conversion for argument 1 from 'double' to 'std::vector<double>&&'
  659 |       vector(vector&& __rv, const __type_identity_t<allocator_type>& __m)
      |              ~~~~~~~~~^~~~
/usr/include/c++/14/bits/stl_vector.h:640:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::vector<_Tp, _Alloc>&&, const allocator_type&, std::false_type) [with _Tp = double; _Alloc = std::allocator<double>; allocator_type = std::allocator<double>; std::false_type = std::false_type]'
  640 |       vector(vector&& __rv, const allocator_type& __m, false_type)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:640:7: note:   candidate expects 3 arguments, 2 provided
/usr/include/c++/14/bits/stl_vector.h:635:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::vector<_Tp, _Alloc>&&, const allocator_type&, std::true_type) [with _Tp = double; _Alloc = std::allocator<double>; allocator_type = std::allocator<double>; std::true_type = std::true_type]'
  635 |       vector(vector&& __rv, const allocator_type& __m, true_type) noexcept
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:635:7: note:   candidate expects 3 arguments, 2 provided
/usr/include/c++/14/bits/stl_vector.h:624:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(const std::vector<_Tp, _Alloc>&, std::__type_identity_t<_Alloc>&) [with _Tp = double; _Alloc = std::allocator<double>; std::__type_identity_t<_Alloc> = std::allocator<double>]'
  624 |       vector(const vector& __x, const __type_identity_t<allocator_type>& __a)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:624:28: note:   no known conversion for argument 1 from 'double' to 'const std::vector<double>&'
  624 |       vector(const vector& __x, const __type_identity_t<allocator_type>& __a)
      |              ~~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/stl_vector.h:620:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::vector<_Tp, _Alloc>&&) [with _Tp = double; _Alloc = std::allocator<double>]'
  620 |       vector(vector&&) noexcept = default;
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:620:7: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_vector.h:601:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(const std::vector<_Tp, _Alloc>&) [with _Tp = double; _Alloc = std::allocator<double>]'
  601 |       vector(const vector& __x)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:601:7: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_vector.h:569:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(size_type, const value_type&, const allocator_type&) [with _Tp = double; _Alloc = std::allocator<double>; size_type = long unsigned int; value_type = double; allocator_type = std::allocator<double>]'
  569 |       vector(size_type __n, const value_type& __value,
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:569:47: note:   no known conversion for argument 2 from 'std::vector<double>' to 'const std::vector<double>::value_type&' {aka 'const double&'}
  569 |       vector(size_type __n, const value_type& __value,
      |                             ~~~~~~~~~~~~~~~~~~^~~~~~~
/usr/include/c++/14/bits/stl_vector.h:556:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(size_type, const allocator_type&) [with _Tp = double; _Alloc = std::allocator<double>; size_type = long unsigned int; allocator_type = std::allocator<double>]'
  556 |       vector(size_type __n, const allocator_type& __a = allocator_type())
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:556:51: note:   no known conversion for argument 2 from 'std::vector<double>' to 'const std::vector<double>::allocator_type&' {aka 'const std::allocator<double>&'}
  556 |       vector(size_type __n, const allocator_type& __a = allocator_type())
      |                             ~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:542:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(const allocator_type&) [with _Tp = double; _Alloc = std::allocator<double>; allocator_type = std::allocator<double>]'
  542 |       vector(const allocator_type& __a) _GLIBCXX_NOEXCEPT
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:542:7: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_vector.h:531:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector() [with _Tp = double; _Alloc = std::allocator<double>]'
  531 |       vector() = default;
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:531:7: note:   candidate expects 0 arguments, 2 provided
a.cc:35:106: error: template argument 1 is invalid
   35 |         vector<vector<vector<double>>> dp (aa + 1, vector < vector<double>(bb + 1, vector<double>(cc + 1)));
      |                                                                                                          ^
a.cc:35:106: error: template argument 2 is invalid