bzoj1013

这道题题解太多，只贴代码。

 #include<cstdio>

 #include<cmath>

 #include<algorithm>

 using namespace std ;

 const int MAXN =  ;

 double value [ MAXN ] [ MAXN ] ;

 double ans [ MAXN ] ;

 int N ;

 void print () {

     for ( int i =  ; i < N ; ++ i ) {

         for ( int j =  ; j <= N ; ++ j ) printf ( "%.6lf " , value [ i ] [ j ] ) ;

         putchar ( '\n' ) ;

     }

     putchar ( '\n' ) ;

 }

 void Gauss () {

     for ( int i =  ; i < N ; ++ i ) {

         {

             int p = i ;

             for ( int j = i +  ; j < N ; ++ j )

                 if ( fabs ( value [ p ] [ i ] ) < fabs ( value [ j ] [ i ] ) ) p = j ;

             swap_ranges ( value [ i ] , value [ i ] + N +  , value [ p ] ) ;

         }

         {

             const double d = 1.0 / value [ i ] [ i ] ;

             for ( int j =  ; j <= N ; ++ j ) value [ i ] [ j ] *= d ;

         }

         for ( int j =  ; j < N ; ++ j ) {

             if ( j == i ) continue ;

             const double d = value [ j ] [ i ] ;

             for ( int k =  ; k <= N ; ++ k ) value [ j ] [ k ] -= d * value [ i ] [ k ] ;

         }

     }

 }

 double x [ MAXN ] [ MAXN ] ;

 int main () {

     scanf ( "%d" , & N ) ;

     for ( int i =  ; i <= N ; ++ i )

         for ( int j =  ; j < N ; ++ j ) scanf ( "%lf" , & x [ i ] [ j ] ) ;

     for ( int i =  ; i < N ; ++ i ) x [ i ] [ N ] = 0.0 ;

     for ( int i =  ; i < N ; ++ i ) {

         for ( int j =  ; j < N ; ++ j ) {

             value [ i ] [ j ] =  * ( x [ i ] [ j ] - x [ i +  ] [ j ] ) ;

             value [ i ] [ N ] += x [ i ] [ j ] * x [ i ] [ j ] - x [ i +  ] [ j ] * x [ i +  ] [ j ] ;

         }

     }

     Gauss () ;

     printf ( "%.3lf" , value [  ] [ N ] ) ;

     for ( int i =  ; i < N ; ++ i ) printf ( " %.3lf" , value [ i ] [ N ] ) ;

     return  ;

 }