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  ;
 }