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=0; i<tot; i++ ) 
        b[i] = a[i];
    for( int i=60,j=0; i>=0 && j<tot; i-- ) {
        for( int k=j; k<tot; k++ )
            if( (b[k]>>i) & 1 ) {
                swap( b[k], b[j] );
                break;
            }
        if( (b[j]>>i)==1 ) {
            for( int k=j+1; k<tot; k++ )
                if( (b[k]>>i) & 1 ) {
                    b[k] ^= b[j];
                    if( b[k]==0 ) return false;
                }
            j++;
        }
    }
    return true;
}
int main() {
    scanf( "%d", &n );
    for( int i=1; i<=n; i++ ) 
        prs[i].read();
    sort( prs+1, prs+1+n );
    int ans = 0;
    for( int i=n; i>=1; i-- ) {
        a[tot++] = prs[i].v;
        if( ok() ) {
            ans += prs[i].w;
        } else {
            tot--;
        }
    }
    printf( "%d
", ans );
}