【HDOJ】5046 Airport

DLX简单题目。

/* 5046 */
#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 int maxn = 65;
int N, K;
__int64 X[maxn], Y[maxn];
__int64 M[maxn][maxn];

typedef struct {
    static const int maxc = 65;
    static const int maxr = 65;
    static const int maxn = 65*65+5;
    
    int n, sz;
    int S[maxc];
    
    int col[maxn];
    int L[maxn], R[maxn], U[maxn], D[maxn];
    
    int ansd;
    bool visit[maxc];
    
    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;
        
        sz = n + 1;
        memset(S, 0, sizeof(S));
    }
    
    void addRow(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;
            
            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];
        }
    }
    
    void restore(int c) {
        for (int i=D[c]; i!=c; i=D[i]) {
            L[R[i]] = i;
            R[L[i]] = i;
        }
    }
    
    int H() {
        int ret = 0;
        
        memset(visit, false, sizeof(visit));
        
        for (int c=R[0]; c!=0; c=R[c]) {
            if (visit[c])
                continue;
            ++ret;
            visit[c] = true;
            for (int i=D[c]; i!=c; i=D[i]) {
                for (int j=R[i]; j!=i; j=R[j]) {
                    visit[col[j]] = true;
                }
            }
        }
        
        return ret;
    }
    
    bool dfs(int d) {
        if (R[0] == 0) {
            return d<=K;
        }
        
        int delta = H();
        if (d+delta > K)
            return false;
        
        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);
            }
            if( dfs(d + 1) )    return true;
            for (int j=L[i]; j!=i; j=L[j]) {
                restore(j);
            }
            restore(i);
        }
        
        return false;
    }
    
} DLX;

DLX solver;

__int64 Length(int i, int j) {
    return abs(X[i]-X[j]) + abs(Y[i]-Y[j]);
}

bool judge(__int64 d) {
    solver.init(N);
    
    rep(i, 1, N+1) {
        vi columns;
        rep(j, 1, N+1) {
            if (M[i][j] <= d) {
                columns.pb(j);
            }
        }
        if (SZ(columns) > 0) {
            solver.addRow(columns);
        }
    }
    
    return solver.dfs(0);
}

void solve() {
    rep(i, 1, N+1) {
        M[i][i] = 0;
        rep(j, 1, i)
            M[i][j] = M[j][i] = Length(i, j);
    }
    
    __int64 l, r, mid;
    __int64 ans;
    
    l = 0;
    r = ans = 5e9;
    while (r >= l) {
        mid = (r + l)>>1;
        if (judge(mid)) {
            ans = mid;
            r = mid - 1;
        } else {
            l = mid + 1;
        }
    }
    
    printf("%I64d
", ans);
}

int main() {
    ios::sync_with_stdio(false);
    #ifndef ONLINE_JUDGE
        freopen("data.in", "r", stdin);
        freopen("data.out", "w", stdout);
    #endif
    
    int t;
    
    scanf("%d", &t);
    rep(tt, 1, t+1) {
        scanf("%d %d", &N, &K);
        rep(i, 1, N+1)
            scanf("%I64d %I64d", &X[i], &Y[i]);
        printf("Case #%d: ", tt);
        solve();
    }
    
    #ifndef ONLINE_JUDGE
        printf("time = %d.
", (int)clock());
    #endif
    
    return 0;
}