optimized_kmp

#include <iostream>
#include <vector>
#include <string>

void form_suffix_array(std::vector<int>& pi, std::string& a) {
    int j = 0, i = 1;
    while (i < a.length()) {
        if (a[i] != a[j]) {
            if (j == 0 && pi[i] == 0) {
                ++i;
            }
            else {
                j = pi[j - 1];
            }
        }
        else {
            pi[i] = j + 1;
            ++i;
            ++j;
        }
    }
}

void print_str(std::string& str, int start, int end) {
    //std::cout << start << " " << end << '\n';
    if (start == end) return;
    start = start > str.length() ? start - str.length() : start;
    end = end > str.length() ? end - str.length() : end;
    for (int i = start; i < end; ++i) {
        std::cout << str[i];
    }
    std::cout << '\n';
}
//←→↑↓
auto print_space = [](int j) {for (int i = 0; i < j; ++i) std::cout << " ";};

void display_current_pointer_position(std::string& a, std::string& t, int i, int j) {
    print_space(i);
    std::cout << "|\n";
    print_str(a, 0, a.length());
    print_space(i - j);
    print_str(t, 0, t.length());
    print_space(i);
    std::cout << "|\n\n";
}

std::vector<int> kmp(char a, std::string& t, std::vector<int>& pi) {
    std::vector<int> res;
    int m = t.length();
    int i = 0, j = 0;
    while (a != '.') {
        if (a == t[j]) {
            ++i; ++j;
            if (j == m) {
                res.push_back(i - m);
            }
            std::cin >> a;
        }
        else {
            if (j > 0) {
                //display_current_pointer_position(a, t, i, j);
                j = pi[j - 1];
            }
            else {
                ++i;
                std::cin >> a;
            }
        }
        //display_current_pointer_position(a, t, i, j);
    }
    if (res.size() == 0) {
        res.push_back(-1);
    }
    return res;
}

//лилилось лилилась

int main() {
    std::string p;
    std::cin >> p;
    //std::string t;
    //std::cin >> t;
    std::vector<int> pi(p.length(), 0);
    form_suffix_array(pi, p);
    char a;
    std::cin >> a;
    std::vector<int> res = kmp(a, p, pi);
    for (int i = 0; i < res.size(); ++i) {
        if (i < res.size() - 1)
            std::cout << res[i] << ',';
        else
            std::cout << res[i];
    }
    std::cout << '\n';
    return 0;
}