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

 

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#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; }