题目

先贴代码

#include <bits/stdc++.h>

//#define debug

using namespace std;

namespace mihomo
{
	inline const bool
	equal(const double& __x,
		  const double& __y)
	{ return fabs(__x-__y) < 1e-9; }
	
	class gaussian
	{
	private:
		int _row;
		int _col;
		double** _LHS;
		double* _RHS;
		int _statue;
		
	public:
		gaussian(int __row, int __col)
		: _row(__row), _col(__col)
		{
			_LHS = new double* [_row];
			_RHS = new double [_row] ();
			int __i, __j;
			for (__i = 0; __i < _row; __i++)
				_LHS[__i] = new double [_col] ();
			_statue = 0;
		}

		~gaussian(void)
		{
			int __i;
			for (__i = 0; __i < _row; __i++)
				delete [] (_LHS[__i]);
			delete [] (_LHS);
			delete [] (_RHS);
		}

		inline double*
		operator[](int __pos)
		{ return _LHS[__pos]; }

		inline double&
		operator()(int __pos)
		{ return _RHS[__pos]; }

		friend inline ostream&
		operator<<( ostream& os,
					gaussian& __x )
		{
			int __i, __j;
			os << "--------------------------------\n";
			for (__i = 0; __i < __x._row; __i++)
			{
				for (__j = 0; __j < __x._col; __j++)
					os << __x[__i][__j] << ' ';
				os << "|" << __x._RHS[__i] << endl;
			}
			os << "--------------------------------\n";
		}

		inline const int&
		solve(void)
		{
			int __i, __j, __k, __mx, __nw;
			double __coef;
			for (__k = 0; __k < _row && __k < _col; __k++)
			{
#ifdef debug
				cout << (*this);
#endif
				__mx = __nw;
				for (__i = __nw + 1; __i < _row; __i++)
					if (abs(_LHS[__i][__k]) > abs(_LHS[__mx][__k]))
						__mx = __i;
				if (equal(_LHS[__mx][__k], 0)) continue;
				if (__mx != __nw)
					swap(_LHS[__mx], _LHS[__nw]),
					swap(_RHS[__mx], _RHS[__nw]);
#ifdef debug
				cout << (*this);
#endif
				__coef = _LHS[__nw][__k];
				for (__j = __k; __j < _col; __j++)
					_LHS[__nw][__j] /= __coef;
				_RHS[__nw] /= __coef;
#ifdef debug
				cout << (*this);
#endif
				for (__i = 0; __i < _row; __i++)
				{
					if (__i == __nw) continue;
					__coef = _LHS[__i][__k];
					for (__j = __k; __j < _col; __j++)
						_LHS[__i][__j] -= __coef * _LHS[__nw][__j];
					_RHS[__i] -= __coef * _RHS[__nw];
				}
				__nw++;
#ifdef debug
				cout << (*this);
#endif
			}
			if (__nw == _row) return _statue = 1;
			while (__nw < _row)
				if (!equal(_RHS[__nw++], 0)) return _statue = -1;
			return _statue = INT_MAX;
		}
		
		inline const int&
		statue(void) const
		{ return _statue; }
	};
};

using namespace mihomo;

int main(void)
{
	int n, x;
	cin >> n;
	gaussian equations(n, n);
	for (int i(0); i < n; i++)
	{
		for (int j(0); j < n; j++)
		{
			cin >> x;
			equations[i][j] = (double)x;
		}
		cin >> x;
		equations(i) = (double)x;
	}
	if (equations.solve() == 1)
		for (int i(0); i < n; i ++)
			cout << fixed << setprecision(2) << 'x' << i+1 << '=' << equations(i) << endl;
	else if (equations.statue() == -1) cout << -1;
	else cout << 0;
	
	return 0;	
}

此代码在c++14(GCC 9)(不开O2)下AC记录详情

在C++14开启O2下40pts记录详情

在c++11\c++14不开启O2下0ptsRE记录详情 记录详情

在c++14(GCC 9)开启O2下0ptsRE记录详情

概况如下

以上RE皆为Segmentation fault with invalid memory reference.（即访问非法内存错误） 保证代码与贴中代码相同 有没有神犇帮本蒟蒻解释一下(违规紫砂)