【HDOJ】2295 Radar

DLX+二分。

 /* 2295 */
 #include <iostream>
 #include <string>
 #include <map>
 #include <queue>
 #include <set>
 #include <stack>
 #include <vector>
 #include <deque>
 #include <algorithm>
 #include <cstdio>
 #include <cmath>
 #include <ctime>
 #include <cstring>
 #include <climits>
 #include <cctype>
 #include <cassert>
 #include <functional>
 #include <iterator>
 #include <iomanip>
 using namespace std;
 //#pragma comment(linker,"/STACK:102400000,1024000")

 #define sti                set<int>
 #define stpii            set<pair<int, int> >
 #define mpii            map<int,int>
 #define vi                vector<int>
 #define pii                pair<int,int>
 #define vpii            vector<pair<int,int> >
 #define rep(i, a, n)     for (int i=a;i<n;++i)
 #define per(i, a, n)     for (int i=n-1;i>=a;--i)
 #define clr                clear
 #define pb                 push_back
 #define mp                 make_pair
 #define fir                first
 #define sec                second
 #define all(x)             (x).begin(),(x).end()
 #define SZ(x)             ((int)(x).size())
 #define lson            l, mid, rt<<1
 #define rson            mid+1, r, rt<<1|1

 const double eps = 1e-;
 const int maxn = ;
 int N, M, K;
 double cx[maxn], cy[maxn];
 double rx[maxn], ry[maxn];
 bool visit[maxn];

 typedef struct {
     static const int maxc = ;
     static const int maxr = ;
     static const int maxn = maxr * maxc;

     int n, sz;
     int S[maxc];

     int row[maxn], col[maxn];
     int L[maxn], R[maxn], U[maxn], D[maxn];

     int ansd;

     void init(int n_) {
         n = n_;

         rep(i, , n+) {
             L[i] = i - ;
             R[i] = i + ;
             U[i] = i;
             D[i] = i;
             col[i] = i;
         }

         L[] = n;
         R[n] = ;

         ansd = INT_MAX;
         sz = n+;
         memset(S, , sizeof(S));
     }

     void addRow(int r, vi columns) {
         int first = sz;
         int size = SZ(columns);

         rep(i, , size) {
             int c = columns[i];

             L[sz] = sz - ;
             R[sz] = sz + ;

             D[sz] = c;
             U[sz] = U[c];
             D[U[c]] = sz;
             U[c] = sz;

             row[sz] = r;
             col[sz] = c;

             ++S[c];
             ++sz;
         }

         L[first] = sz - ;
         R[sz - ] = first;
     }

     void remove(int c) {
         for (int i=D[c]; i!=c; i=D[i]) {
             L[R[i]] = L[i];
             R[L[i]] = R[i];
             --S[col[i]];
         }
     }

     void restore(int c) {
         for (int i=D[c]; i!=c; i=D[i]) {
             L[R[i]] = i;
             R[L[i]] = i;
             ++S[col[i]];
         }
     }

     int H() {
         int ret = ;

         memset(visit, false, sizeof(visit));
         for (int i=R[]; i!=; i=R[i]) {
             if (visit[col[i]])
                 continue;
             ++ret;
             visit[col[i]] = true;
             for (int j=D[i]; j!=i; j=D[j]) {
                 for (int k=R[j]; k!=j; k=R[k]) {
                     visit[col[k]] = true;
                 }
             }
         }

         return ret;
     }

     void dfs(int d) {
         int delta = H();

         if (delta+d>=ansd || d+delta>K)
             return ;

         if (R[] == ) {
             ansd = min(ansd, d);
             return ;
         }

         int c = R[];
         for (int i=R[]; i!=; i=R[i]) {
             if (S[i] < S[c])
                 c = i;
         }

         for (int i=D[c]; i!=c; i=D[i]) {
             remove(i);
             for (int j=R[i]; j!=i; j=R[j]) {
                 remove(j);
             }
             dfs(d + );
             if (ansd <= K)
                 return ;
             for (int j=L[i]; j!=i; j=L[j]) {
                 restore(j);
             }
             restore(i);
         }
     }

 } DLX;

 DLX solver;

 double Length(int j, int i) {
     return sqrt((cx[i]-rx[j])*(cx[i]-rx[j]) + (cy[i]-ry[j])*(cy[i]-ry[j]));
 }

 bool judge(double bound) {
     memset(visit, false, sizeof(visit));
     solver.init(N);

     rep(i, , M+) {
         vi columns;
         int cnt = ;
         rep(j, , N+) {
             if (Length(i, j) <= bound) {
                 columns.pb(j);
                 visit[j] = true;
                 ++cnt;
             }
         }

         if (SZ(columns) > ) {
             solver.addRow(i, columns);
         }
     }

     rep(j, , N+) {
         if (!visit[j]) {
     #ifndef ONLINE_JUDGE
     // printf("ansd = %d\n", solver.ansd);
     #endif
             return false;
         }
     }

     solver.dfs();

     #ifndef ONLINE_JUDGE
     // printf("ansd = %d\n", solver.ansd);
     #endif
     return solver.ansd<=K;
 }

 int main() {
     ios::sync_with_stdio(false);
     #ifndef ONLINE_JUDGE
         freopen("data.in", "r", stdin);
         freopen("data.out", "w", stdout);
     #endif

     double ans;
     double l, r, mid;
     int t;

     scanf("%d", &t);
     while (t--) {
         scanf("%d %d %d", &N, &M, &K);
         rep(i, , N+)
             scanf("%lf %lf", &cx[i], &cy[i]);
         rep(i, , M+)
             scanf("%lf %lf", &rx[i], &ry[i]);
         l = ;
         r = ans = 2000.0;
         while (r >= l) {
             mid = (r + l) / 2.0;
             if (judge(mid)) {
                 ans = min(ans, mid);
                 r = mid - eps;
             } else {
                 l = mid + eps;
             }
         }
         printf("%.06lf\n", ans);
     }

     #ifndef ONLINE_JUDGE
         printf("time = %d.\n", (int)clock());
     #endif

     return ;
 }