KMP字符串匹配算法--算法导论示例zz

The Knuth-Morris-Pratt string searching algorithm searches for occurrences of a "pattern" string within a main string by employing the simple observation that when a mismatch occurs, we have enough knowledge simply by possessing the pattern to determine where the next match could begin, thus bypassing re-examination of previously matched characters.

#include <iostream>

int *ComputePrefixFunction(char *p)
...{
    int m=strlen(p);
    int *c=new int[m];
    memset(c,0,m*sizeof(int));
    c[0]=0;
    int k=0;
    for(int q=2;q<=m;q++)
    ...{
        while(k>0&&p[k]!=p[q-1])
            k=c[k-1];
        if(p[k]==p[q-1])
            k=k+1;
        c[q-1]=k;
    }

    return c;
}

void KMP_Matcher(char *t,char *p)
...{
    int n=strlen(t);
    int m=strlen(p);
    int *c=new int[m];
    memset(c,0,m*sizeof(int));
    c=ComputePrefixFunction(p);
    int q=0;
    
    for(int i=1;i<=n;i++)
    ...{
        while(q>0&&p[q]!=t[i-1])
            q=c[q-1];
        if(p[q]==t[i-1])
            q=q+1;
        if(q==m)
        ...{
            printf("Pattern occurs with shift %d ",i-m+1);
            q=c[q-1];
        }
    }
}

int main()
...{
    KMP_Matcher("dsfdsfsshefgfdgshedsfdfshe","she");
    return 0;
}