magyarsort/gptsort.h

#include <cmath>
#include <vector>
#include <algorithm>

// ChatGPT and me did this space partitioning bucket sort
void gpt_bucket_sort(uint32_t* array, int n) {
  // Calculate the number of buckets to use
  int num_buckets = std::sqrt(n);

  // Create a vector of buckets
  std::vector<std::vector<uint32_t>> buckets(num_buckets);

  // Calculate the range of values that each bucket can hold
  uint32_t min_value = *std::min_element(array, array + n);
  uint32_t max_value = *std::max_element(array, array + n);
  uint32_t range = max_value - min_value + 1;
  uint32_t bucket_size = range / num_buckets + 1;

  // Distribute the elements of the array into the buckets
  for (int i = 0; i < n; i++) {
    // Calculate the bucket index for this element
    // using the range of values and the bucket size as the divisor
    int bucket_index = (array[i] - min_value) / bucket_size;
    buckets[bucket_index].push_back(array[i]);
  }

  // Sort the elements in each bucket using std::sort
  for (int i = 0; i < num_buckets; i++) {
    std::sort(buckets[i].begin(), buckets[i].end());
  }

  // Concatenate the buckets to get the sorted array
  int k = 0;
  for (int i = 0; i < num_buckets; i++) {
    for (int j = 0; j < buckets[i].size(); j++) {
      array[k++] = buckets[i][j];
    }
  }
}

// Further optimizations (no chatGPT)
void my_bucket_sort(uint32_t* array, int n) {
  // Calculate the number of buckets to use
  int num_buckets = std::sqrt(n);

  // Create a vector of buckets
  std::vector<std::vector<uint32_t>> buckets(num_buckets);

  // Calculate the range of values that each bucket can hold
  auto mm = std::minmax_element(array, array + n);
  uint32_t min_value = *mm.first;
  uint32_t max_value = *mm.second;
  uint32_t range = max_value - min_value + 1;
  uint32_t bucket_size = range / num_buckets + 1;

  // Distribute the elements of the array into the buckets
  for (int i = 0; i < n; i++) {
    // Calculate the bucket index for this element
    // using the range of values and the bucket size as the divisor
    int bucket_index = (array[i] - min_value) / bucket_size;
    buckets[bucket_index].push_back(array[i]);
  }

  // Sort the elements in each bucket using std::sort
  for (int i = 0; i < num_buckets; i++) {
    std::sort(buckets[i].begin(), buckets[i].end());
  }

  // Concatenate the buckets to get the sorted array
  int k = 0;
  for (int i = 0; i < num_buckets; i++) {
    for (int j = 0; j < buckets[i].size(); j++) {
      array[k++] = buckets[i][j];
    }
  }
}