Problem Descripition

You are given 2 strings,text and pattern , you should do the following operations

1. If pattern is not in text, goto 4

2. delete the first occurrence of pattern in text

3. goto 1

4. print current text

5. end

I try to solve this problem using KMP Algorithm. I find the delete operation will cost much time, so I use another textNext array to store the next element's index of text string to skip the pattern string in text(avoiding really deleting it from text). For example, text is ukpkmkk, and the pattern is pk. After executing the operations, textNext should be {1,4,3,4,5,6,7}(textNext is initialized to i+1 for element). I use the code below to traverse the string after those operations.

for (int i = 0; i < text.length(); i = textNext[i]) {...}

My problem is that I can't get the correct result using my algorithm. Here is my code.

    public static void main(String[] args) {
        String text = in.next();
        String pattern = in.next();
        int[] textNext = new int[text.length()];
        for (int i = beginIndex; i < textNext.length; i++) {
            textNext[i] = i + 1;
        }

        while (kmp(text, pattern, textNext) != -1) {}

        for (int i = beginIndex; i < text.length(); i = textNext[i]) {
            out.print(text.charAt(i));
        }
        out.println("");
        out.close();
    }

    public static int kmp(String text, String pattern, int[] textNext) {
        int[] patternNext = buildNext(pattern);
        int head = 0;
        for (int i = beginIndex, j = 0; i < text.length(); i = textNext[i]) {
            while (j > 0 && text.charAt(i) != pattern.charAt(j)) {
                j = patternNext[j - 1];
            }
            if (text.charAt(i) == pattern.charAt(j)) {
                if (j == 0) {
                    head = i;
                }
                j++;
            }
            if (j == pattern.length()) {
                if (head == 0) {
                    beginIndex = i + 1;
                } else {
                    textNext[head - 1] = i + 1;
                }
                return head;
            }
        }
        return -1;
    }

    public static int[] buildNext(String pattern) {
        int[] next = new int[pattern.length()];
        next[0] = 0;
        for (int i = 1, j = 0; i < next.length; i++) {
            while (j > 0 && pattern.charAt(i) != pattern.charAt(j)) {
                j = next[j - 1];
            }
            if (pattern.charAt(i) == pattern.charAt(j)) {
                j++;
            }
            next[i] = j;
        }
        return next;
    }

Please point out where my algorithm's problem is or just offer other way to solve this problem.