【数论】zoj3870

就是找一个区间内使得a亦或b>max(a,b);

然后如果a的最高位是1然后对应b的位置是0然后b还大于1<<（h-1）(h代表a的最高位1)；

找出所有这样的数对，

所以就先排个序，把他们归结到各个某一位为零的vector里然后对于每一个数在对应的vector里二分查找就好了

#include<iostream>#include<cstdio>#include<cmath>#include<cstdlib>#include<algorithm>#include<cstring>#include<vector>using namespace std;int cmp(int x,int y) {return x>y;}int a[100100];vector<int> vec[34];int main(){freopen("test.in","r",stdin);freopen("test.out","w",stdout);int t,n;long long sum;scanf("%d",&t);while (t--){sum=0;scanf("%d",&n);memset(a,0,sizeof(a));for (int i=1;i<=30;i++)vec[i].clear();for (int i=1;i<=n;i++)scanf("%d",&a[i]);sort(a+1,a+n+1,cmp);for (int i=1;i<=n;i++)for (int j=1;j<=30;j++)if ((a[i]|(1<<(j-1)))!=a[i]) vec[j].push_back(a[i]);for (int i=1;i<=n;i++){int k=0;for (int j=1;j<=30;j++)if ((a[i]|(1<<(j-1)))==a[i])k=j;int l=-1,r=vec[k].size()-1,mid;while (l!=r){mid=((l+r)>>1)+1;if (vec[k][mid]>a[i]) l=mid;else r=mid-1;}sum+=l+1;}printf("%d\n",sum);}return 0;}