【模板】字符串系列算法

一、KMP

CODE：

#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
#define rep(i,a,n) for(int i = a;i <= n;i++)
#define per(i,n,a) for(int i = n;i >= a;i--)
#define inf 2147483647
#define ms(a,b) memset(a,b,sizeof(a))
using namespace std;
typedef long long ll;
ll read() {
    ll as = 0,fu = 1;
    char c = getchar();
    while(c < '0' || c > '9') {
        if(c == '-') fu = -1;
        c = getchar();
    } 
    while(c >= '0' && c <= '9') {
        as = as * 10 + c - '0';
        c = getchar();
    }
    return as * fu;
}
const int N = 1000005;
//head

int nxt[N];
char s[N],t[N];

void init(int m) {
    int tmp = 0;
    rep(i,2,m) {
        while(tmp && t[tmp+1] != t[i]) 
            tmp = nxt[tmp];
        if(t[tmp+1] == t[i]) nxt[i] = ++tmp;
    }
}

void KMP(int n,int m) {
    int tmp = 0;
    rep(i,1,n) {
        while(tmp && t[tmp+1] != s[i]) tmp = nxt[tmp];
        if(t[tmp+1] == s[i]) {
            tmp++;
            if(tmp == m) printf("%d\n",i-tmp+1);
        }
    }
}

int main() {
    scanf("%s",s+1);
    scanf("%s",t+1);
    int n = strlen(s+1);
    int m = strlen(t+1);
    init(m);
    KMP(n,m);
    rep(i,1,m) printf("%d ",nxt[i]);
    puts("");
    return 0;
}

 

 

二、manacher

CODE：

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
#define rep(i,a,n) for(int i = a;i <= n;i++)
#define per(i,n,a) for(int i = n;i >= a;i--)
#define ms(a,b) memset(a,b,sizeof a)
#define inf 2147483647
using namespace std;
typedef long long ll;
ll read() {
    ll as = 0,fu = 1;
    char c = getchar();
    while(c < '0' || c > '9') {
    if(c == '-') fu = -1;
    c = getchar();
    }
    while(c >= '0' && c <= '9') {
    as = as * 10 + c - '0';
    c = getchar();
    }
    return as * fu;
}
const int N = 20000005;
//head
int n,ans,top;
char m[N],s[N<<1];
int len[N];//'#' --> x/2.0 --> len
void init() {
    top = 0;
    s[top] = '#';
    s[++top] = '#';
    n = strlen(m);
    rep(i,0,n-1) {
    s[++top] = m[i];
    s[++top] = '#';
    }
    s[++top] = 0;
}

void manacher() {
    int mr = 0,mid;
    rep(i,1,top-1) {
           if(i < mr) len[i] = min(len[(mid<<1)-i],len[mid] + mid - i);
    else len[i] = 1;
    while(s[i + len[i]] == s[i - len[i]]) len[i]++;
    if(len[i] + i > mr) {
        mr = len[i] + i;
        mid = i;
    }
    }
}



int main() {
    scanf("%s",m);
    init();
//    puts(s);
    manacher();
    rep(i,0,top-1) ans = max(ans,len[i]);
    printf("%d\n",ans-1);
    return 0;
}

三、AC_automaton

Code：

#include<cstdio>
#include<algorithm>
#include<cstring>
#include<cmath>
#include<queue> 
#define rep(i,a,n) for(int i = a;i <= n;i++)
#define per(i,n,a) for(int i = n;i >= a;i--)
#define enter putchar('\n')

using namespace std;
const int N = 500005;
const int M = 1000005;
typedef long long ll;

int read()
{
    int ans = 0,op = 1;
    char ch = getchar();
    while(ch < '0' || ch > '9')
    {
    if(ch == '-') op = -1;
    ch = getchar();
    }
    while(ch >= '0' && ch <= '9')
    {
    ans *= 10;
    ans += ch - '0';
    ch = getchar();
    }
    return ans * op;
}

queue<int> q;
int t,sum[200],maxn;
char str[M],s[200][200];
struct ACG
{
    int c[N][26],p[N],fail[N],cnt,d[N];
    void clear()
    {
    memset(c,0,sizeof(c));
    memset(fail,0,sizeof(fail));
    memset(d,0,sizeof(d));
    memset(p,0,sizeof(p));
    cnt = 0;
    }
    void insert(char *s,int f)
    {
    int len = strlen(s),now = 0;
    rep(i,0,len-1)
    {
        int v = s[i] - 'a';
        if(!c[now][v]) c[now][v] = ++cnt;
        now = c[now][v];
    }
    p[now]++,d[now] = f;
    }
    void getfail()
    {
    rep(i,0,25) if(c[0][i]) fail[c[0][i]] = 0,q.push(c[0][i]);
    while(!q.empty())
    {
        int k = q.front();q.pop();
        rep(i,0,25)
        {
        if(c[k][i]) fail[c[k][i]] = c[fail[k]][i],q.push(c[k][i]);
        else c[k][i] = c[fail[k]][i];
        }
    }
    }
    void match(char *s)
    {
    int len = strlen(s),now = 0;
    rep(i,0,len-1)
    {
        now = c[now][s[i] - 'a'];
        for(int g = now;g && p[g] != -1;g = fail[g])
        {
        if(p[g]) sum[d[g]]++;
        //else p[g] = -1;
        }
    }
    }
}AC;
int main()
{
    while(1)
    {
    t = read(); if(!t) break;
    AC.clear(),memset(sum,0,sizeof(sum)),maxn = 0;
    rep(i,1,t) scanf("%s",s[i]),AC.insert(s[i],i);
    AC.getfail();
    scanf("%s",str),AC.match(str);
    rep(i,1,t) maxn = max(maxn,sum[i]);
    printf("%d\n",maxn);
    rep(i,1,t) if(sum[i] == maxn) printf("%s\n",s[i]);
    }
    return 0;
}