KMP prefix table

Question

I am reading about KMP for string matching.
It needs a preprocessing of the pattern by building a prefix table.
For example for the string ababaca

Answer 1

String pattern = "ababaca";

int i = 1, j = 0;

int[] prefixArray = new int[pattern.length];

while (i < pattern.length) {

    while (pattern.charAt(i) != pattern.charAt(j) && j > 0) {
        j = prefixArray[j - 1];

    }

    if (pattern.charAt(i) == pattern.charAt(j)) {
        prefixArray[i] = j + 1;
        i++;
        j++;

    } else {
        prefixArray[i] = j;
        i++;
    }
}

for (int k = 0; k < prefixArray.length; ++k) {
    cout<< prefixArray[k]<< endl;
}