3105: [cqoi2013]新Nim游戏

14年论文题

贪心+线性基搞一搞

忘了开longlong一直WA好智障阿QAQ

#include<iostream>#include<cstdio>#include<cstring>#include<algorithm>#include<vector>using namespace std;#define rep(i,l,r) for(int i=l;i<=r;i++)#define per(i,r,l) for(int i=r;i>=l;i--)#define mmt(a,v) memset(a,v,sizeof(a))typedef long long ll;int a[105];int base[40];bool ins(int x){per(i,30,0)if((x>>i)&1){if(!base[i]){base[i]=x;return true;}else x^=base[i];}return !(!x);}int main(){freopen("a.in","r",stdin);int n;scanf("%d",&n);ll ans=0,sum;rep(i,1,n)scanf("%d",&a[i]),ans+=a[i];sum=ans;sort(a+1,a+1+n);per(i,n,1)if(ins(a[i]))ans-=a[i];if(sum==ans)ans=-1;printf("%lld\n",ans);return 0;}