Function algorithm_prev_permutation

algorithm/algorithm.c:1153–1188

* @brief Generates the previous lexicographical permutation of a range. * * This function rearranges the elements in the range `[first, last)` into the previous lexicographical * permutation, as determined by the comparison function `comp`. If such a permutation is not possible, * the range is rearranged into the largest lexicographical order (sorted in descending order). * * @param first Po

 * @return `true` if the previous permutation was generated, `false` if the range was reset to the largest permutation.
 */
bool algorithm_prev_permutation(void *first, void *last, size_t size, CompareFuncBool comp) {
    ALGORITHM_LOG("[algorithm_prev_permutation] Info: Generating previous permutation.");
    if (first == last) {
        ALGORITHM_LOG("[algorithm_prev_permutation] Warning: Empty range, returning false.");
        return false;
    }

    char *i = (char *)last - size;
    while (i != (char *)first) {
        char *j = i;
        i -= size;

        if (comp(j, i)) {
            char *k = (char *)last - size;
            
            while (!comp(k, i)) {
                k -= size;
            }

            ALGORITHM_LOG("[algorithm_prev_permutation] Info: Swapping elements.");
            swap(i, k, size);
            reverse(j, last, size);

            ALGORITHM_LOG("[algorithm_prev_permutation] Success: Previous permutation generated.");
            return true;
        }
        if (i == (char *)first) {
            ALGORITHM_LOG("[algorithm_prev_permutation] Info: Resetting to largest permutation.");
            
            reverse(first, last, size);
            return false;
        }
    }

    return false; 
}


/**