kmp poj 3461

来源：互联网发布：动态sql防止sql注入编辑：程序博客网时间：2024/05/22 12:59

这是一道KMP的水题，还没明白KMP是怎么回事 ==，先贴了代码，明天继续研究。

#include <stdio.h>#include <string.h>const int MaxN = 1000010;char word[MaxN/10], txt[MaxN];int next[MaxN/10];void KMP_next(char b[], int pre[]){    int n = (int)strlen(b), k;    pre[0] = -1; k = -1;    for(int i = 1; i < n; i++)    {        while(k > -1 && b[k+1] != b[i]) k = pre[k];        if(b[k+1] == b[i]) k++;        pre[i] = k;    }}int main(){    int n;    for(scanf("%d%*c", &n); n--;)    {        gets(word); gets(txt);        KMP_next(word, next);        int cnt = 0, len = (int)strlen(word);        for(int i = 0, j = -1; txt[i]; ++i)        {             while(j > -1 && word[j+1] != txt[i])                 j = next[j];             if(word[j+1] == txt[i])                 j++;             if(j == len-1) {                 cnt++; j = next[j];             }         }         printf("%d\n", cnt);     }     return 0;}

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