• LA 4670 Dominating Patterns (AC自动机)


    题意:给定一个一篇文章,然后下面有一些单词,问这些单词在这文章中出现过几次。

    析:这是一个AC自动机的裸板,最后在匹配完之后再统计数目就好。

    代码如下:

    #pragma comment(linker, "/STACK:1024000000,1024000000")
    #include <cstdio>
    #include <string>
    #include <cstdlib>
    #include <cmath>
    #include <iostream>
    #include <cstring>
    #include <set>
    #include <queue>
    #include <algorithm>
    #include <vector>
    #include <map>
    #include <cctype>
    #include <cmath>
    #include <stack>
    #define debug puts("+++++")
    //#include <tr1/unordered_map>
    #define freopenr freopen("in.txt", "r", stdin)
    #define freopenw freopen("out.txt", "w", stdout)
    using namespace std;
    //using namespace std :: tr1;
    
    typedef long long LL;
    typedef pair<int, int> P;
    const int INF = 0x3f3f3f3f;
    const double inf = 0x3f3f3f3f3f3f;
    const LL LNF = 0x3f3f3f3f3f3f;
    const double PI = acos(-1.0);
    const double eps = 1e-8;
    const int maxn = 1e6 + 5;
    const LL mod = 2147493647;
    const int N = 1e6 + 5;
    const int dr[] = {-1, 0, 1, 0, 1, 1, -1, -1};
    const int dc[] = {0, 1, 0, -1, 1, -1, 1, -1};
    const char *Hex[] = {"0000", "0001", "0010", "0011", "0100", "0101", "0110", "0111", "1000", "1001", "1010", "1011", "1100", "1101", "1110", "1111"};
    inline LL gcd(LL a, LL b){  return b == 0 ? a : gcd(b, a%b); }
    inline int gcd(int a, int b){  return b == 0 ? a : gcd(b, a%b); }
    inline int lcm(int a, int b){  return a * b / gcd(a, b); }
    int n, m;
    const int mon[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
    const int monn[] = {0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
    inline int Min(int a, int b){ return a < b ? a : b; }
    inline int Max(int a, int b){ return a > b ? a : b; }
    inline LL Min(LL a, LL b){ return a < b ? a : b; }
    inline LL Max(LL a, LL b){ return a > b ? a : b; }
    inline bool is_in(int r, int c){
        return r >= 0 && r < n && c >= 0 && c < m;
    }
    const int sigma = 26;
    const int maxnode = 70 * 150 + 5;
    
    struct Aho{
        int cnt[155];
        int ch[maxnode][sigma];
        int f[maxnode];
        int val[maxnode];
        int last[maxnode];
        int sz;
        void init(){
            sz = 1;
            memset(ch[0], 0, sizeof ch[0]);
            memset(cnt, 0, sizeof cnt);
        }
    
        int idx(char ch){  return ch - 'a'; }
    
        void print(int j){
            if(j){
                ++cnt[val[j]];
                print(last[j]);
            }
        }
        void insert(char *s, int v){
            int u = 0;
            while(*s){
                int c = idx(*s);
                if(!ch[u][c]){
                    memset(ch[sz], 0, sizeof ch[sz]);
                    val[sz] = 0;
                    ch[u][c] = sz++;
                }
                u = ch[u][c];  ++s;
            }
            val[u] = v;
    
        }
    
        void find(char *s){
            int j = 0;
            while(*s){
                int c = idx(*s);
                while(j && !ch[j][c]) j = f[j];
                j = ch[j][c];
                if(val[j]) print(j);
                else if(last[j])  print(last[j]);
                ++s;
            }
        }
    
        void getFail(){
            queue<int> q;
            f[0] = 0;
            for(int c = 0; c < sigma; ++c){
                int u = ch[0][c];
                if(u){ f[u] = 0;  q.push(u);  last[u] = 0; }
            }
    
            while(!q.empty()){
                int r = q.front();  q.pop();
                for(int c = 0;c < sigma; ++c){
                    int u = ch[r][c];
                    if(!u)  continue;
                    q.push(u);
                    int v = f[r];
                    while(v && !ch[v][c]) v = f[v];
                    f[u] = ch[v][c];
                    last[u] = val[f[u]] ? f[u] : last[f[u]];
                }
            }
        }
    };
    
    Aho aho;
    char s[155][75];
    char t[1000005];
    map<string, int> mp;
    
    int main(){
        while(scanf("%d", &n) == 1 && n){
            aho.init();
            mp.clear();
            for(int i = 1; i <= n; ++i){
                scanf("%s", s[i]);
                aho.insert(s[i], i);
                mp[s[i]] = i;
            }
            scanf("%s", t);
            aho.getFail();
            aho.find(t);
            int mmax = -1;
            for(int i = 1; i <= n; ++i)  mmax = Max(mmax, aho.cnt[i]);
            printf("%d
    ", mmax);
            for(int i = 1; i <= n; ++i)
                if(aho.cnt[mp[s[i]]] == mmax)  printf("%s
    ", s[i]);
        }
        return 0;
    }
    
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  • 原文地址:https://www.cnblogs.com/dwtfukgv/p/6031416.html
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