【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-8;
const int maxn = 60;
int N, M, K;
double cx[maxn], cy[maxn];
double rx[maxn], ry[maxn];
bool visit[maxn];

typedef struct {
    static const int maxc = 65;
    static const int maxr = 65;
    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, 0, n+1) {
            L[i] = i - 1;
            R[i] = i + 1;
            U[i] = i;
            D[i] = i;
            col[i] = i;
        }
        
        L[0] = n;
        R[n] = 0;
        
        ansd = INT_MAX;
        sz = n+1;
        memset(S, 0, sizeof(S));
    }
    
    void addRow(int r, vi columns) {
        int first = sz;
        int size = SZ(columns);
        
        rep(i, 0, size) {
            int c = columns[i];
            
            L[sz] = sz - 1;
            R[sz] = sz + 1;
            
            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 - 1;
        R[sz - 1] = 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 = 0;
        
        memset(visit, false, sizeof(visit));
        for (int i=R[0]; i!=0; 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[0] == 0) {
            ansd = min(ansd, d);
            return ;
        }
        
        int c = R[0];
        for (int i=R[0]; i!=0; 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 + 1);
            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, 1, M+1) {
        vi columns;
        int cnt = 0;
        rep(j, 1, N+1) {
            if (Length(i, j) <= bound) {
                columns.pb(j);
                visit[j] = true;
                ++cnt;
            }
        }

        if (SZ(columns) > 0) {
            solver.addRow(i, columns);
        }
    }
    
    rep(j, 1, N+1) {
        if (!visit[j]) {
    #ifndef ONLINE_JUDGE
    // printf("ansd = %d
", solver.ansd);
    #endif
            return false;
        }
    }
    
    solver.dfs(0);
    
    #ifndef ONLINE_JUDGE
    // printf("ansd = %d
", 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, 1, N+1)
            scanf("%lf %lf", &cx[i], &cy[i]);
        rep(i, 1, M+1)
            scanf("%lf %lf", &rx[i], &ry[i]);
        l = 0;
        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
", ans);
    }

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

    return 0;
}