//KMP算法
public class KMP {
    private String pat;
    private int[][] dfa;

    public KMP(String pat) {
        int len = pat.length();
        this.pat = pat;
        int R =256;
        dfa = new int[R][len];
        dfa[pat.charAt(0)][0] = 1;
        for (int X = 0, j =1;j< len;j++) {
            for (int c =0; c < R;c++) {
                dfa[c][j] = dfa[c][X];
            }
            dfa[pat.charAt(j)][j] = j+1;
            X = dfa[pat.charAt(j)][X];
        }
    }

    public int search(String txt) {
        int N = txt.length();
        int M = pat.length();
        int i,j;
        for (i = 0,j = 0;i < N && j <M;i++) {
            j = dfa[txt.charAt(i)][j];
        }
        if (j == M) return i - M;
        else    return N;
    }
}

//Boyer-Moore算法
public class BM {
    private String pat;
    private int[] right;

    public BM(String pat) {
        this.pat = pat;
        int M = pat.length();
        int R =256;
        right = new int[R];
        for (int i = 0;i< R;i++) right[i] = -1;
        for (int i = 0; i < M; i++) right[pat.charAt(i)] = i;
    }

    public int search(String txt) {
        int i, j,skip;
        int M =pat.length();
        int N = txt.length();

        for (i = 0; i < N - M; i += skip) {
            skip = 0;
            for (j = M-1;j >= 0;j--) {
                if (pat.charAt(j) != txt.charAt(i + j)) {
                    skip = j - right[txt.charAt(i + j)];
                    if (skip < 1) skip = 1;
                    break;
                }
                if (skip == 0) return i;
            }
            return N;
        }

    }
}

//Rabin-Karp算法
public class RK {
    private long patHash; // pattern hash value
    private int M; // pattern length
    private final int R = 256; // radix
    private int Q = 997;
    private long RM;

    public RK(String pat) {
        M = pat.length();
        patHash = hash(pat, M);
        for (int i = 1; i <= M-1; i++)
            RM = (R * RM) % Q;
    }

    private long hash(String pat, int M) {
        long h = 0;
        for (int j = 0;j < M ;j++) {
            h = (R * h + pat.charAt(j)) % Q;
        }
        return h;
    }

    public int search(String txt) {
        int N = txt.length();
        long txtHash = hash(txt, M);
        if (patHash == txtHash) return 0;
        for (int i = M; i < N;i++) {
            txtHash = (txtHash + Q - RM*txt.charAt(i-M) % Q) % Q;
            txtHash = (txtHash*R + txt.charAt(i)) % Q;
            if (patHash == txtHash) return i - M + 1;
        }
        return N;
    }
}