HDU 4016 搜索

/********************************************************************************剪个枝就过了～比赛的时候没什么人做，主要是因为位运算的威慑力太大了～********************************************************************************/#include <iostream>#include <algorithm>#include <complex>#include <cstdlib>#include <cstring>#include <utility>#include <bitset>#include <cstdio>#include <memory>#include <string>#include <vector>#include <cmath>#include <ctime>#include <queue>#include <stack>#include <list>#include <map>#include <set>using namespace std;#define lowbit(x) ( (x) & ( (x) ^ (x - 1) ) )//typedef long long LL;//typedef unsigned long long ULL;typedef __int64 LL;typedef unsigned __int64 ULL;typedef pair<int, int> PII;typedef pair<double, double> PDD;typedef map<int, int>::iterator MI;typedef vector<int>::iterator VI;typedef list<LL>::iterator LI;typedef set<int>::iterator SI;const int INF_INT = 0x3f3f3f3f;const LL INF_LL = 0x7fffffffffffffff;const double oo = 10e9;const double eps = 10e-7;const double PI = acos(-1.0);const int MAXN = 44;int test, n, m;LL ans, arr[MAXN];bool check(int id, LL buf){for (int i = id + 1; i < n; ++i){buf &= arr[i];}return buf < ans;}void dfs(int crt, int step, LL buf){ans = min(ans, buf);if (step >= m){return ;}for (int nxt = crt + 1; nxt < n; ++nxt){LL tmp = buf & arr[nxt];if (!check(nxt, tmp)){continue ;}dfs(nxt, step + 1, tmp);}return ;}void ace(){int cas = 1;for (scanf("%d", &test); test--; ++cas){scanf("%d %d", &n, &m);for (int i = 0; i < n; ++i){scanf("%I64d", arr + i);}sort(arr, arr + n);ans = INF_LL;for (int i = 0; i < n; ++i){dfs(i, 1, arr[i]);}printf("Case #%d: %I64d\n", cas, ans);}return ;}int main(){ace();return 0;}