HDU 3949 XOR

3949

思路：

线性基，线性基的每个元素尽可能小

将k转换成二进制与排好序的线性基相对应

如果线性基的个数小于n，说明n个元素线性相关，所以可以构成0，k要减1

代码：

#pragma GCC optimize(2)
#pragma GCC optimize(3)
#pragma GCC optimize(4)
#include<bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define pi acos(-1.0)
#define LL long long
#define mp make_pair
#define pb push_back
#define ls rt<<1, l, m
#define rs rt<<1|1, m+1, r
#define ULL unsigned LL
#define pll pair<LL, LL>
#define pii pair<int, int>
#define piii pair<pii, int>
#define mem(a, b) memset(a, b, sizeof(a))
#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);
//head

vector<LL> base;
int main() {
    int T, n, q;
    LL t;
    scanf("%d", &T);
    for (int cs = 1; cs <= T; cs++) {
        scanf("%d", &n);
        base.clear();
        for (int i = 0; i < n; i++) {
            scanf("%lld", &t);
            for (int j = 0; j < base.size(); j++) t = min(t, t^base[j]);
            if(t) base.pb(t);
        }
        sort(base.begin(), base.end()); 
        int m = base.size();
        for (int i = 1; i < m; i++) {
            for (int j = i-1; j >= 0; j--) {
                base[i] = min(base[i], base[i]^base[j]);
            }
        }
        scanf("%d", &q);
        printf("Case #%d:
", cs);
        while(q--) {
            scanf("%lld", &t);
            if(m < n) t--;
            if(t >= (1LL << m)) {
                printf("-1
");
                continue;
            }
            LL ans = 0;
            for (int j = 0; j < m; j++) if((t>>j)&1) ans ^= base[j];
            printf("%lld
", ans); 
        }
    }    
    return 0;
}