#include <vector>
#include <iostream>

using namespace std;

int fuzzy_substring(const string needle,
                    const string haystack) {
    const int nlen = needle.size(),
              hlen = haystack.size();
    if (hlen == 0) return -1;
    if (nlen == 1) return haystack.find(needle);
    vector<int> row1(hlen+1, 0);
    for (int i = 0; i < nlen; ++i) {
        vector<int> row2(1, i+1);
        for (int j = 0; j < hlen; ++j) {
            const int cost = needle[i] != haystack[j];
            row2.push_back(std::min(row1[j+1]+1,
                                    std::min(row2[j]+1,
                                             row1[j]+cost)));
        }
        row1.swap(row2);
    }
    return *std::min_element(row1.begin(), row1.end());
}

int main()
{
    cout << "Substring match ('aa', 'bb aca bb'): " << fuzzy_substring("aa", "bb aca bb") << endl ;
    return 0 ;
}