bool sumsTo(unsigned int x[], unsigned int n, unsigned int k, unsigned int v) {
    if (v == 0 && k == 0) { return true; }  // sum = 0 and elemLeft = 0
    if (v < 0 || n == 0) { return false; }  // negative, not possible or array empty
    return (sumsTo(x, n - 1, k - 1, v - x[n - 1]) || sumsTo(x, n - 1, k, v));       // three line solution fuck yeah