public class ccase12_KMP {
    public static void main(String[] args) {
        String s = "babababcbabababb";
        // String p="bababb";
        String p = "bab";
        System.out.println(work(s, p));

    }

    /**
     * 求出现模式串的次数
     * 
     * @param s
     * @param p
     */
    private static int work(String s, String p) {
        int len1 = s.length();
        int len2 = p.length();
        int i = 0, j = 0;
        int count = 0;
        int[] next = next(p);
        // 异常处理
        if (len1 < len2)
            return -1;
        if (len1 == 0 || len2 == 0)
            return -1;

        while (i < len1) {
            if (j == -1 || s.charAt(i) == p.charAt(j)) {
                i++;
                j++;
            } else {// 失配
                j = next[j];
            }
            if (j == len2) {
                count++;
                i--;
                j = next[j];
                // return (i-j);
            }

        }
        return count;
    }

    public static int[] next(String p1) {
        int[] next = new int[p1.length() + 1];
        char[] p = p1.toCharArray();
        next[0] = -1;
        if (p1.length() == 1)
            return next;
        next[1] = 0;
        int j = 1;
        int k = next[j];
        while (j < p1.length()) {
            if (k < 0 || p[j] == p[k]) {
                next[++j] = ++k;
            } else {
                k = next[k];
            }
        }

        return next;
    }

}