马拉车——模版+KMP——模版

Posted 2020-10-09 DDYYZZ

void Manacher(){
    for (int i=0;t[i];++i,len+=2){
        s[i<<1]=‘#‘;
        if (t[i]>=‘A‘&&t[i]<=‘Z‘) s[i<<1|1]=t[i]-‘A‘+‘a‘;
        else s[i<<1|1]=t[i];
    }
    s[len++]=‘#‘;
    int max_r=0,pos=0;
    for (int i=0;i<len;++i){
        if (max_r>i) r[i]=min(max_r-i,r[2*pos-i]);
        else r[i]=0;
        while (i+r[i]+1<len&&i-r[i]-1>=0&&s[i+r[i]+1]==s[i-r[i]-1]) r[i]++;
        if (r[i]+i>max_r){
            max_r=r[i]+i;
            pos=i;
        }
    }
}
//马拉车

#define N 1010
char s[N],p[N];
int nxt[N];
void get_nxt(char * p){
    int i=0,j=-1; nxt[i]=j;
    while (p[i]){
        if (j==-1||p[j]==p[i]) nxt[++i]=++j;
        else j=nxt[j];
    }
}

int kmp(char *s,char *p){
    get_nxt(p);
    int i=0,j=0,ret=0;
    for (;s[i];++i){
        while (j!=-1&&s[i]!=p[j]) j=nxt[j];
        j++;
        if (!p[j]){
            ret++; j=next[j];
            //operations
        }
    }
    return ret;
}

int main(){
    
    scanf("%s%s",s,p);
    printf("%d\n",kmp(s,p));
    
    return 0;
}
//KMP算法