bzoj 2460 拟阵+判线性相关

 /**************************************************************
     Problem: 2460
     User: idy002
     Language: C++
     Result: Accepted
     Time:68 ms
     Memory:832 kb
 ****************************************************************/

 #include <cstdio>
 #include <algorithm>
 #define N 1010
 using namespace std;

 typedef unsigned long long dnt;

 struct Pair {
     dnt v;
     int w;
     void read() { scanf( "%llu%d", &v, &w ); }
     bool operator<( const Pair &p ) const { return w<p.w; }
 };

 int n;
 Pair prs[N];
 dnt a[N], b[N]; int tot;

 bool ok() {
     for( int i=; i<tot; i++ )
         b[i] = a[i];
     for( int i=,j=; i>= && j<tot; i-- ) {
         for( int k=j; k<tot; k++ )
             if( (b[k]>>i) &  ) {
                 swap( b[k], b[j] );
                 break;
             }
         if( (b[j]>>i)== ) {
             for( int k=j+; k<tot; k++ )
                 if( (b[k]>>i) &  ) {
                     b[k] ^= b[j];
                     if( b[k]== ) return false;
                 }
             j++;
         }
     }
     return true;
 }
 int main() {
     scanf( "%d", &n );
     for( int i=; i<=n; i++ )
         prs[i].read();
     sort( prs+, prs++n );
     int ans = ;
     for( int i=n; i>=; i-- ) {
         a[tot++] = prs[i].v;
         if( ok() ) {
             ans += prs[i].w;
         } else {
             tot--;
         }
     }
     printf( "%d\n", ans );
 }