264 lines
8.2 KiB
C++
264 lines
8.2 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___RANDOM_DISCRETE_DISTRIBUTION_H
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#define _LIBCPP___RANDOM_DISCRETE_DISTRIBUTION_H
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#include <__algorithm/upper_bound.h>
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#include <__config>
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#include <__random/is_valid.h>
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#include <__random/uniform_real_distribution.h>
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#include <cstddef>
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#include <iosfwd>
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#include <numeric>
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#include <vector>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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_LIBCPP_PUSH_MACROS
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#include <__undef_macros>
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_LIBCPP_BEGIN_NAMESPACE_STD
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template<class _IntType = int>
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class _LIBCPP_TEMPLATE_VIS discrete_distribution
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{
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static_assert(__libcpp_random_is_valid_inttype<_IntType>::value, "IntType must be a supported integer type");
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public:
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// types
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typedef _IntType result_type;
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class _LIBCPP_TEMPLATE_VIS param_type
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{
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vector<double> __p_;
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public:
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typedef discrete_distribution distribution_type;
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_LIBCPP_INLINE_VISIBILITY
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param_type() {}
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template<class _InputIterator>
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_LIBCPP_INLINE_VISIBILITY
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param_type(_InputIterator __f, _InputIterator __l)
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: __p_(__f, __l) {__init();}
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#ifndef _LIBCPP_CXX03_LANG
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_LIBCPP_INLINE_VISIBILITY
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param_type(initializer_list<double> __wl)
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: __p_(__wl.begin(), __wl.end()) {__init();}
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#endif // _LIBCPP_CXX03_LANG
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template<class _UnaryOperation>
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param_type(size_t __nw, double __xmin, double __xmax,
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_UnaryOperation __fw);
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vector<double> probabilities() const;
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friend _LIBCPP_INLINE_VISIBILITY
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bool operator==(const param_type& __x, const param_type& __y)
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{return __x.__p_ == __y.__p_;}
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friend _LIBCPP_INLINE_VISIBILITY
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bool operator!=(const param_type& __x, const param_type& __y)
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{return !(__x == __y);}
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private:
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void __init();
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friend class discrete_distribution;
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template <class _CharT, class _Traits, class _IT>
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friend
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basic_ostream<_CharT, _Traits>&
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operator<<(basic_ostream<_CharT, _Traits>& __os,
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const discrete_distribution<_IT>& __x);
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template <class _CharT, class _Traits, class _IT>
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friend
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basic_istream<_CharT, _Traits>&
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operator>>(basic_istream<_CharT, _Traits>& __is,
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discrete_distribution<_IT>& __x);
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};
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private:
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param_type __p_;
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public:
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// constructor and reset functions
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_LIBCPP_INLINE_VISIBILITY
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discrete_distribution() {}
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template<class _InputIterator>
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_LIBCPP_INLINE_VISIBILITY
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discrete_distribution(_InputIterator __f, _InputIterator __l)
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: __p_(__f, __l) {}
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#ifndef _LIBCPP_CXX03_LANG
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_LIBCPP_INLINE_VISIBILITY
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discrete_distribution(initializer_list<double> __wl)
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: __p_(__wl) {}
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#endif // _LIBCPP_CXX03_LANG
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template<class _UnaryOperation>
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_LIBCPP_INLINE_VISIBILITY
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discrete_distribution(size_t __nw, double __xmin, double __xmax,
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_UnaryOperation __fw)
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: __p_(__nw, __xmin, __xmax, __fw) {}
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_LIBCPP_INLINE_VISIBILITY
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explicit discrete_distribution(const param_type& __p)
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: __p_(__p) {}
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_LIBCPP_INLINE_VISIBILITY
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void reset() {}
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// generating functions
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template<class _URNG>
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_LIBCPP_INLINE_VISIBILITY
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result_type operator()(_URNG& __g)
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{return (*this)(__g, __p_);}
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template<class _URNG> result_type operator()(_URNG& __g, const param_type& __p);
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// property functions
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_LIBCPP_INLINE_VISIBILITY
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vector<double> probabilities() const {return __p_.probabilities();}
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_LIBCPP_INLINE_VISIBILITY
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param_type param() const {return __p_;}
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_LIBCPP_INLINE_VISIBILITY
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void param(const param_type& __p) {__p_ = __p;}
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_LIBCPP_INLINE_VISIBILITY
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result_type min() const {return 0;}
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_LIBCPP_INLINE_VISIBILITY
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result_type max() const {return __p_.__p_.size();}
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friend _LIBCPP_INLINE_VISIBILITY
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bool operator==(const discrete_distribution& __x,
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const discrete_distribution& __y)
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{return __x.__p_ == __y.__p_;}
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friend _LIBCPP_INLINE_VISIBILITY
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bool operator!=(const discrete_distribution& __x,
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const discrete_distribution& __y)
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{return !(__x == __y);}
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template <class _CharT, class _Traits, class _IT>
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friend
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basic_ostream<_CharT, _Traits>&
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operator<<(basic_ostream<_CharT, _Traits>& __os,
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const discrete_distribution<_IT>& __x);
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template <class _CharT, class _Traits, class _IT>
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friend
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basic_istream<_CharT, _Traits>&
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operator>>(basic_istream<_CharT, _Traits>& __is,
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discrete_distribution<_IT>& __x);
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};
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template<class _IntType>
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template<class _UnaryOperation>
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discrete_distribution<_IntType>::param_type::param_type(size_t __nw,
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double __xmin,
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double __xmax,
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_UnaryOperation __fw)
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{
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if (__nw > 1)
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{
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__p_.reserve(__nw - 1);
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double __d = (__xmax - __xmin) / __nw;
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double __d2 = __d / 2;
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for (size_t __k = 0; __k < __nw; ++__k)
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__p_.push_back(__fw(__xmin + __k * __d + __d2));
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__init();
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}
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}
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template<class _IntType>
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void
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discrete_distribution<_IntType>::param_type::__init()
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{
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if (!__p_.empty())
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{
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if (__p_.size() > 1)
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{
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double __s = _VSTD::accumulate(__p_.begin(), __p_.end(), 0.0);
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for (vector<double>::iterator __i = __p_.begin(), __e = __p_.end(); __i < __e; ++__i)
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*__i /= __s;
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vector<double> __t(__p_.size() - 1);
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_VSTD::partial_sum(__p_.begin(), __p_.end() - 1, __t.begin());
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swap(__p_, __t);
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}
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else
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{
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__p_.clear();
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__p_.shrink_to_fit();
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}
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}
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}
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template<class _IntType>
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vector<double>
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discrete_distribution<_IntType>::param_type::probabilities() const
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{
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size_t __n = __p_.size();
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vector<double> __p(__n+1);
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_VSTD::adjacent_difference(__p_.begin(), __p_.end(), __p.begin());
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if (__n > 0)
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__p[__n] = 1 - __p_[__n-1];
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else
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__p[0] = 1;
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return __p;
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}
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template<class _IntType>
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template<class _URNG>
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_IntType
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discrete_distribution<_IntType>::operator()(_URNG& __g, const param_type& __p)
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{
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static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");
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uniform_real_distribution<double> __gen;
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return static_cast<_IntType>(
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_VSTD::upper_bound(__p.__p_.begin(), __p.__p_.end(), __gen(__g)) -
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__p.__p_.begin());
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}
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template <class _CharT, class _Traits, class _IT>
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_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
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operator<<(basic_ostream<_CharT, _Traits>& __os,
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const discrete_distribution<_IT>& __x)
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{
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__save_flags<_CharT, _Traits> __lx(__os);
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typedef basic_ostream<_CharT, _Traits> _OStream;
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__os.flags(_OStream::dec | _OStream::left | _OStream::fixed |
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_OStream::scientific);
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_CharT __sp = __os.widen(' ');
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__os.fill(__sp);
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size_t __n = __x.__p_.__p_.size();
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__os << __n;
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for (size_t __i = 0; __i < __n; ++__i)
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__os << __sp << __x.__p_.__p_[__i];
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return __os;
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}
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template <class _CharT, class _Traits, class _IT>
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_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
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operator>>(basic_istream<_CharT, _Traits>& __is,
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discrete_distribution<_IT>& __x)
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{
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__save_flags<_CharT, _Traits> __lx(__is);
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typedef basic_istream<_CharT, _Traits> _Istream;
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__is.flags(_Istream::dec | _Istream::skipws);
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size_t __n;
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__is >> __n;
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vector<double> __p(__n);
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for (size_t __i = 0; __i < __n; ++__i)
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__is >> __p[__i];
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if (!__is.fail())
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swap(__x.__p_.__p_, __p);
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return __is;
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}
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_LIBCPP_END_NAMESPACE_STD
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_LIBCPP_POP_MACROS
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#endif // _LIBCPP___RANDOM_DISCRETE_DISTRIBUTION_H
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