KMP!

    #include <stdio.h>

    int kmp(char *text, char *target, int failure_array[])
    {
            int start = 0, cur = 0;
            while (text[start + cur] != '\0')
            {
                    if (target[cur] == '\0')
                    {
                            return 1;
                    }
                    if (target[cur] == text[start + cur])
                    {
                            cur++;
                    }
                    else
                    {
                            start = start + cur - failure_array[cur];
                            cur = failure_array[cur];
                            if (cur < 0)
                                    cur = 0;
                    }
            }
            return target[cur] == '\0';
    }

    void initialise_array(char *target, int failure_array[], int n)
    {
            for (int i = 0; i < n; i++)
            {
                    failure_array[i] = 0;
                    for (int postfix_start = 1; postfix_start < i; postfix_start++)
                    {
                            int postfix_size = i - postfix_start;
                            int match = 1;
                            // Check if postfix matches the prefix
                            for (int prefix_i = 0; prefix_i < postfix_size; prefix_i++)
                            {
                                    if (target[prefix_i] != target[postfix_start + prefix_i])
                                    {
                                            match = 0;
                                    }
                            }
                            if (match)
                            {
                                    failure_array[i] = postfix_size;
                                    break;
                            }
                    }
            }
            failure_array[0] = -1;
    }

    int main(int argc, char *argv[])
    {
            char *target = "cart cars";
            int failure_array[9];
            initialise_array(target, failure_array, 9);
            for (int i = 0; i < 9; i++)
            {
                    printf("%d ", failure_array[i]);
            }
            printf("\n");
            char *text = "cars cart cars";
            printf("%d\n", kmp(text, target, failure_array));
    }