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;
}