[C++]KMP算法实现

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KMP算法说明：http://zh.wikipedia.org/wiki/%E5%85%8B%E5%8A%AA%E6%96%AF-%E8%8E%AB%E9%87%8C%E6%96%AF-%E6%99%AE%E6%8B%89%E7%89%B9%E7%AE%97%E6%B3%95

#include<string>using namespace std;class KMP{public:    KMP(string);    int search(string txt);private:    string pat;    static const int R = 256;    int* dfa[R];    int M;};KMP::KMP(string _pat){    pat = _pat;    M = pat.length();    for (int i = 0; i < R; i++){        dfa[i] = new int[M];        for (int j = 0; j < M; j++){            dfa[i][j] = 0;        }    }    dfa[pat[0]][0] = 1;    for (int X = 0, j = 1; j < M; j++){        for (int c = 0; c < R; c++){            dfa[c][j] = dfa[c][X];        }        dfa[pat[j]][j] = j + 1;        X = dfa[pat[j]][X];    }}int KMP::search(string txt){    int i, j;    int N = txt.length();    for (i = 0, j = 0; i < N&&j < M; i++){        j = dfa[txt[i]][j];    }    if (j == M) //如果找到返回在txt中的位置        return i - M;    else        //找不到则返回txt的长度        return N;}

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