标签:blog os io for div cti sp log on
感觉白书上的做法很神!
首先状压表示电脑之间的联通关系,然后预处理出所有关闭电脑的组合达到的状态,然后枚举每个状态并且枚举每个状态的所有子集,之后无脑递推就木有了。
关于枚举一个状态所有子集的小技巧:假设当前状态是S0
有
for s = s0; s != 0; s = (s - 1) & s0
#include <cstdio> #include <cstring> #include <iostream> #include <map> #include <set> #include <vector> #include <string> #include <queue> #include <deque> #include <bitset> #include <list> #include <cstdlib> #include <climits> #include <cmath> #include <ctime> #include <algorithm> #include <stack> #include <sstream> #include <numeric> #include <fstream> #include <functional> using namespace std; #define MP make_pair #define PB push_back typedef long long LL; typedef unsigned long long ULL; typedef vector<int> VI; typedef pair<int,int> pii; const int INF = INT_MAX / 3; const double eps = 1e-8; const LL LINF = 1e17; const double DINF = 1e60; const int maxn = 16; const int maxs = 1 << maxn; int cpt[maxn], cover[maxs], n; int f[maxs]; int main() { int kase = 1; while(scanf("%d", &n), n) { int all_cover = (1 << n) - 1, ns = (1 << n); memset(cpt,0,sizeof(cpt)); memset(cover,0,sizeof(cover)); memset(f,0,sizeof(f)); for(int i = 0;i < n;i++) { int cnt, tmp; scanf("%d",&cnt); for(int j = 0;j < cnt;j++) { scanf("%d", &tmp); cpt[i] |= (1 << tmp); } cpt[i] |= (1 << i); } for(int i = 0;i < ns;i++) { for(int j = 0;j < n;j++) if(i & (1 << j)) { cover[i] |= cpt[j]; } } for(int i = 0;i < ns;i++) { for(int s = i; s; s = (s - 1) & i) { if(cover[s] == all_cover) { f[i] = max(f[i], f[i ^ s] + 1); } } } printf("Case %d: %d\n", kase++, f[all_cover]); } return 0; }
UVA 11825 Hackers' Crackdown 状压DP
标签:blog os io for div cti sp log on
原文地址:http://www.cnblogs.com/rolight/p/3959164.html