SPOJ 7758. Growing Strings AC自动机DP

Growing Strings

题目：给出n个字符串，问最多能够选出多少个串组成序列，并满足前一个字符串是后一个字符串的子串。

分析：

　　AC自动机经典水题。。。
　　考虑每个节点结尾时，他能够选出最多的串 = max{ 父节点选出  ， fail节点选出 }+以该节点为结尾的单词个数

 

#include <set>

#include <map>

#include <list>

#include <cmath>

#include <queue>

#include <stack>

#include <string>

#include <vector>

#include <cstdio>

#include <cstring>

#include <complex>

#include <iostream>

#include <algorithm>



using namespace std;



typedef long long ll;

typedef unsigned long long ull;



#define debug puts("here")

#define rep(i,n) for(int i=0;i<n;i++)

#define rep1(i,n) for(int i=1;i<=n;i++)

#define REP(i,a,b) for(int i=a;i<=b;i++)

#define foreach(i,vec) for(unsigned i=0;i<vec.size();i++)

#define pb push_back

#define RD(n) scanf("%d",&n)

#define RD2(x,y) scanf("%d%d",&x,&y)

#define RD3(x,y,z) scanf("%d%d%d",&x,&y,&z)

#define RD4(x,y,z,w) scanf("%d%d%d%d",&x,&y,&z,&w)

#define All(vec) vec.begin(),vec.end()

#define MP make_pair

#define PII pair<int,int>

#define PQ priority_queue

#define cmax(x,y) x = max(x,y)

#define cmin(x,y) x = min(x,y)

#define Clear(x) memset(x,0,sizeof(x))

#define lson rt<<1

#define rson rt<<1|1

#define SZ(x) x.size()



/*



#pragma comment(linker, "/STACK:1024000000,1024000000")



int ssize = 256 << 20; // 256MB

char *ppp = (char*)malloc(ssize) + ssize;

__asm__("movl %0, %%esp\n" :: "r"(ppp) );



*/



char IN;

bool NEG;

inline void Int(int &x){

    NEG = 0;

    while(!isdigit(IN=getchar()))

        if(IN=='-')NEG = 1;

    x = IN-'0';

    while(isdigit(IN=getchar()))

        x = x*10+IN-'0';

    if(NEG)x = -x;

}

inline void LL(ll &x){

    NEG = 0;

    while(!isdigit(IN=getchar()))

        if(IN=='-')NEG = 1;

    x = IN-'0';

    while(isdigit(IN=getchar()))

        x = x*10+IN-'0';

    if(NEG)x = -x;

}



/******** program ********************/



const int MAXN = 1e6+5;

const int kind = 26;



char s[MAXN];



struct AC{



    int dp[MAXN];

    int ch[MAXN][kind],fail[MAXN];

    int end[MAXN];

    int tot;



    inline void set(int x){

        Clear(ch[x]);

        fail[x] = end[x] = dp[x] = 0;

    }

    inline void init(){

        set(tot = 1);

    }

    inline int newNode(){

        set(++tot);

        return tot;

    }

    inline int ind(char c){

        return c-'a';

    }



    inline void ins(){

        int r = 1;

        for(int i=0;s[i];i++){

            int c = ind(s[i]);

            if(ch[r][c]==0)

                ch[r][c] = newNode();

            r = ch[r][c];

        }

        ++end[r];

    }



    inline void build(){

        queue<int> q;

        q.push(1);

        while(!q.empty()){

            int r = q.front();

            q.pop();

            rep(c,kind){

                int x = ch[r][c];

                if(!x)continue;

                q.push(x);

                int y = fail[r];

                while(y&&ch[y][c]==0)

                    y = fail[y];

                fail[x] = y?ch[y][c]:1;

                dp[x] = max( dp[r],dp[ fail[x] ] )+end[x];

            }

        }

        cout<<*max_element(dp+1,dp+tot+1)<<endl;

    }



    inline void run(){

        int n;

        while(RD(n),n){

            init();

            getchar();

            rep(i,n){

                gets(s);

                ins();

            }

            build();

        }

    }

}ac;



int main(){



#ifndef ONLINE_JUDGE

    freopen("sum.in","r",stdin);

    //freopen("sum.out","w",stdout);

#endif



    ac.run();



    return 0;

}