KMP-模式匹配

Posted 2020-08-14

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struct KMP{//s为子串,t为原串
    static const int N=10100;
    int next[N];
    void getnext(char *s){
        int lens=strlen(s);
        next[0]=next[1]=0;
        for(int i=1;i<lens;i++){
            int j=next[i];
            while(j&&s[i]!=s[j])j=next[j];
            next[i+1]=s[i]==s[j]?j+1:0;
        }
    }
    int kmp(char *s,char *t){
        int lens=strlen(s),lent=strlen(t),ans=0;
        for(int i=0,j=0;i<lent;i++){
            while(j&&s[j]!=t[i])j=next[j];
            if(s[j]==t[i])j++;
            if(j==lens)ans++;//可重子串 else bu→j=0;
        }
        return ans;
    }
}kmp;