bzoj 2460 拟阵+判线性相关

 

 

 1 /**************************************************************
 2     Problem: 2460
 3     User: idy002
 4     Language: C++
 5     Result: Accepted
 6     Time:68 ms
 7     Memory:832 kb
 8 ****************************************************************/
 9  
10 #include <cstdio>
11 #include <algorithm>
12 #define N 1010
13 using namespace std;
14  
15 typedef unsigned long long dnt;
16  
17 struct Pair {
18     dnt v;
19     int w;
20     void read() { scanf( "%llu%d", &v, &w ); }
21     bool operator<( const Pair &p ) const { return w<p.w; }
22 };
23  
24 int n;
25 Pair prs[N];
26 dnt a[N], b[N]; int tot;
27  
28 bool ok() {
29     for( int i=0; i<tot; i++ ) 
30         b[i] = a[i];
31     for( int i=60,j=0; i>=0 && j<tot; i-- ) {
32         for( int k=j; k<tot; k++ )
33             if( (b[k]>>i) & 1 ) {
34                 swap( b[k], b[j] );
35                 break;
36             }
37         if( (b[j]>>i)==1 ) {
38             for( int k=j+1; k<tot; k++ )
39                 if( (b[k]>>i) & 1 ) {
40                     b[k] ^= b[j];
41                     if( b[k]==0 ) return false;
42                 }
43             j++;
44         }
45     }
46     return true;
47 }
48 int main() {
49     scanf( "%d", &n );
50     for( int i=1; i<=n; i++ ) 
51         prs[i].read();
52     sort( prs+1, prs+1+n );
53     int ans = 0;
54     for( int i=n; i>=1; i-- ) {
55         a[tot++] = prs[i].v;
56         if( ok() ) {
57             ans += prs[i].w;
58         } else {
59             tot--;
60         }
61     }
62     printf( "%d\n", ans );
63 }
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posted @ 2015-05-23 12:03  idy002  阅读(221)  评论(0)    收藏  举报