nav.cpp

#include <iostream>
#include <vector>
#include <string> 
#include <bitset>
#include <algorithm>


#define BITS 4

using Matrix2D = std::vector<std::vector<int>>;

std::vector<int> to_binary(int i) {    
    auto bs = std::bitset<BITS>{i}.to_string();
    std::vector<int> output;
    for(auto c: bs) {
        output.push_back(c == '1'? 1 : 0);       
    }
    return output;
}

Matrix2D to_grid(const std::vector<int> &a) {
    Matrix2D matrix;
    for (auto i: a) {
        matrix.push_back(to_binary(i));   
    }
    return matrix;
}

int find_min_change(const Matrix2D &matrix, const int &i, const int &j, int cost = 0) {
    if ((i < 0 || i + 1 > matrix[0].size()) || (j < 0 || j + 1 > matrix.size())) {
        return cost;
    }   

    if (matrix[j][i] == 0 && j == 0) {
        return find_min_change(matrix, i + 1, j, cost);    
    } 
    if (matrix[j][i] == 0 && j < matrix.size() - 1) {
        return BITS + 1;
    }
   
    
    int min_change = BITS + 1;
    for (int k = -1; k <= 1; k++) {      
        auto x = k == 0 ? 0 : 1;
        int a = find_min_change(matrix, i + k, j + 1, cost + x);
         min_change = std::min(min_change, a);
    } 
    return min_change;
}

int solution(const std::vector<int> & a) {  
    auto matrix = to_grid(a); 
    auto v = find_min_change(matrix, 0, 0, 0);
    return v < matrix.size() ? v : -1;
}

int main() {
    
    
    std::vector<int> A {7, 11, 10, 4};
    auto r = solution(A);

    std::cout << "Result: " << r << "\n";
}