【HDOJ】3957 Street Fighter

一定要注意审题啊，题目说的是选出做少的英雄打败其余处在任何模式下的英雄。
共有Sigma(num of model)个方案，每个方案有Sigma(num of model)+n个决策。
挺不错的一道精确覆盖的题目，最近发现精确覆盖很有意思。

/* 3957 */
#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

typedef struct {
    static const int maxc = 30*3+5;
    static const int maxr = 60;
    static const int maxn = 60*60+5;
    
    int nmodel;
    int n, sz;
    int S[maxc];
    
    int col[maxn];
    int L[maxn], R[maxn], U[maxn], D[maxn];
    bool visit[maxc];
    
    int ansd;
    
    void init(int nmodel_, int n_) {
        ansd = INT_MAX;
        n = n_;
        nmodel = nmodel_;
        
        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) {
        L[R[c]] = L[c];
        R[L[c]] = R[c];
        for (int i=D[c]; i!=c; i=D[i]) {
            for (int j=R[i]; j!=i; j=R[j]) {
                U[D[j]] = U[j];
                D[U[j]] = D[j];
                --S[col[j]];
            }
        }
    }
    
    void restore(int c) {
        L[R[c]] = c;
        R[L[c]] = c;
        for (int i=D[c]; i!=c; i=D[i]) {
            for (int j=R[i]; j!=i; j=R[j]) {
                U[D[j]] = j;
                D[U[j]] = j;
                ++S[col[j]];
            }
        }
    }
    
    void remove_col(int c) {
        for (int i=D[c]; i!=c; i=D[i]) {
            L[R[i]] = L[i];
            R[L[i]] = R[i];
        }
    }
    
    void restore_col(int c) {
        for (int i=D[c]; i!=c; i=D[i]) {
            L[R[i]] = i;
            R[L[i]] = i;
        }
    }
    
    int H() {
        // return 0;
        int ret = 0;
        
        memset(visit, false, sizeof(visit));
        for (int c=R[0]; c!=0&&c<=nmodel; 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;
    }
    
    void dfs(int d) {
        if (R[0]==0 || R[0]>nmodel) {
            ansd = min(ansd, d);
            return ;
        }
        
        int delta = H();
        
        if (d+delta >= ansd)
            return ;
        
        int c = R[0];
        for (int i=R[0]; i!=0&&i<=nmodel; i=R[i]) {
            if (S[i] < S[c])
                c = i;
        }
        
        for (int i=D[c]; i!=c; i=D[i]) {
            remove_col(i);
            for (int j=R[i]; j!=i; j=R[j]) {
                if (col[j] <= nmodel)
                    remove_col(j);
            }
            for (int j=R[i]; j!=i; j=R[j]) {
                if (col[j] > nmodel)
                    remove(col[j]);
            }
            dfs(d + 1);
            for (int j=L[i]; j!=i; j=L[j]) {
                if (col[j] > nmodel)
                    restore(col[j]);
            }
            for (int j=L[i]; j!=i; j=L[j]) {
                if (col[j] <= nmodel)
                    restore_col(j);
            }
            restore_col(i);
        }
    }
    
    void solve() {
        ansd = INT_MAX;
        dfs(0);
    }
    
} DLX;

typedef struct {
    int m, k[2];
    pii p[2][11];
} hero_t;

DLX solver;
int ID[30][2];
int nmodel, n;
hero_t hero[30];

void solve() {
    solver.init(nmodel, n+nmodel);
    
    rep(i, 0, n) {
        rep(j, 0, hero[i].m) {
            // each model has a plan
            vi columns;
            // cover i-th hero
            columns.pb(nmodel+i+1);    
            // cover 0-th plan
            columns.pb(ID[i][0]);
            // may cover 1-th plan
            if (hero[i].m == 2)
                columns.pb(ID[i][1]);
            rep(k, 0, hero[i].k[j]) {
                int role_id = hero[i].p[j][k].fir;
                int model_id = hero[i].p[j][k].sec;
                columns.pb(ID[role_id][model_id]);
            }
            
            solver.addRow(columns);
        }
    }
    
    solver.solve();
    
    printf("%d
", solver.ansd);
}

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", &n);
        nmodel = 0;
        rep(i, 0, n) {
            scanf("%d", &hero[i].m);
            rep(j, 0, hero[i].m) {
                scanf("%d", &hero[i].k[j]);
                rep(k, 0, hero[i].k[j])
                    scanf("%d %d", &hero[i].p[j][k].fir, &hero[i].p[j][k].sec);
                ID[i][j] = ++nmodel;
            }
        }
        printf("Case %d: ", tt);
        solve();
    }
    
    #ifndef ONLINE_JUDGE
        printf("time = %d.
", (int)clock());
    #endif
    
    return 0;
}