【HDOJ】4057 Rescue the Rabbit

挺有意思的一道题目，解法是AC自动机+DP。
AC自动机建立fail指针时，一定要注意结点的属性也需要传递。AC自动机结合了trie和kmp的优点。
需要注意的是，每个模式串仅计算一次，否则这题很难解。

/* 4057 */
#include <iostream>
#include <sstream>
#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 = 15;
const int maxm = 1030;
const int maxl = 105;
char s[maxl];
int W[maxn];
bool dp[2][maxm][maxm];
int n, m, l;

typedef struct {
    static const int maxn = 1025;
    static const int rt = 1;
    int nxt[maxn][4];
    int fail[maxn];
    int f[maxn];
    int m;
    
    void init() {
        m = 1;
        memset(f, 0, sizeof(f));
        memset(nxt, 0, sizeof(nxt));
    }
    
    int newNode() {
        return ++m;
    }    

    int getId(char c) {
        if (c == 'A')    return 0;
        if (c == 'T')    return 1;
        if (c == 'G')    return 2;
        if (c == 'C')    return 3;
        return -1;
    }
    
    void Insert(char *s, int k) {
        int i = 0, id;
        int p = 1, q;
        
        while (s[i]) {
            id = getId(s[i]);
            q = nxt[p][id];
            if (!q)
                q = nxt[p][id] = newNode();
            p = q;
            ++i;
        }
        f[p] |= (1 << k);
    }
    
    void Build() {
        int cur;
        queue<int> Q;
        
        fail[rt] = rt;
        rep(i, 0, 4) {
            if (nxt[rt][i] == 0) {
                nxt[rt][i] = rt;
            } else {
                fail[nxt[rt][i]] = rt;
                Q.push(nxt[rt][i]);
            }
        }
        
        while (!Q.empty()) {
            cur = Q.front();
            Q.pop();
            rep(i, 0, 4) {
                if (nxt[cur][i] == 0) {
                    nxt[cur][i] = nxt[fail[cur]][i];
                } else {
                    fail[nxt[cur][i]] = nxt[fail[cur]][i];
                    f[nxt[cur][i]] |= f[nxt[fail[cur]][i]];
                    Q.push(nxt[cur][i]);
                }
            }
        }
    }
    
} AC;

AC ac;

int calw(int x) {
    int ret = 0;
    
    rep(i, 0, n) {
        if (x & (1<<i))
            ret += W[i];
    }
    
    return ret;
}

void solve() {
    int ans = INT_MIN;
    int mst = 1<<n, nst, nxt;
    int p = 0, q = 1;
    
    m = ac.m;
    memset(dp, 0, sizeof(dp));
    dp[0][ac.rt][0] = true;
    rep(i, 1, l+1) {
        memset(dp[q], 0, sizeof(dp[q]));
        rep(j, 1, m+1) {
            rep(k, 0, 4) {
                rep(st, 0, mst) {
                    if (dp[p][j][st]) {
                        nxt = ac.nxt[j][k];
                        nst = st | ac.f[nxt];
                        dp[q][nxt][nst] = true;
                    }
                }
            }
        }
        p = q;
        q ^= 1;
    }
    
    rep(st, 0, mst) {
        rep(j, 1, m+1) {
            if (dp[p][j][st]) {
                ans = max(ans, calw(st));
                break;
            }
        }
    }
    
    if (ans < 0)
        puts("No Rabbit after 2012!");
    else
        printf("%d
", ans);
}

int main() {
    ios::sync_with_stdio(false);
    #ifndef ONLINE_JUDGE
        freopen("data.in", "r", stdin);
        freopen("data.out", "w", stdout);
    #endif
    
    int len, w;
    
    while (scanf("%d %d",&n,&l) != EOF) {
        ac.init();
        rep(i, 0, n) {
            scanf("%s %d", s, &W[i]);
            ac.Insert(s, i);
        }
            
        ac.Build();
        solve();
    }
    
    #ifndef ONLINE_JUDGE
        printf("time = %d.
", (int)clock());
    #endif
    
    return 0;
}