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// src/sort.rs
use pyo3::prelude::*;
use pyo3::types::PyList;
/// Merges two subarrays of `arr`.
///
/// # Arguments
///
/// * `arr` - The array to be sorted.
/// * `left` - The starting index of the left subarray.
/// * `mid` - The ending index of the left subarray and starting index of the right subarray.
/// * `right` - The ending index of the right subarray.
fn merge(arr: &mut [i32], left: usize, mid: usize, right: usize) {
let mut left_part = arr[left..mid+1].to_vec();
let mut right_part = arr[mid+1..right+1].to_vec();
left_part.push(i32::MAX);
right_part.push(i32::MAX);
let mut i = 0;
let mut j = 0;
for k in left..=right {
if left_part[i] <= right_part[j] {
arr[k] = left_part[i];
i += 1;
} else {
arr[k] = right_part[j];
j += 1;
}
}
}
/// Recursively divides the array into subarrays and merges them in sorted order.
///
/// # Arguments
///
/// * `arr` - The array to be sorted.
/// * `left` - The starting index of the subarray to be sorted.
/// * `right` - The ending index of the subarray to be sorted.
fn merge_sort_helper(arr: &mut [i32], left: usize, right: usize) {
if left < right {
let mid = left + (right - left) / 2;
merge_sort_helper(arr, left, mid);
merge_sort_helper(arr, mid + 1, right);
merge(arr, left, mid, right);
}
}
/// Partitions the array into two parts and returns the index of the pivot element.
///
/// # Arguments
///
/// * `arr` - The array to be partitioned.
/// * `low` - The starting index of the subarray to be partitioned.
/// * `high` - The ending index of the subarray to be partitioned.
///
/// # Returns
///
/// The index of the pivot element.
fn partition(arr: &mut [i32], low: usize, high: usize) -> usize {
let pivot = arr[high];
let mut i = low;
for j in low..high {
if arr[j] < pivot {
arr.swap(i, j);
i += 1;
}
}
arr.swap(i, high);
i
}
/// Recursively sorts the array using the Quick Sort algorithm.
///
/// # Arguments
///
/// * `arr` - The array to be sorted.
/// * `low` - The starting index of the subarray to be sorted.
/// * `high` - The ending index of the subarray to be sorted.
fn quick_sort_helper(arr: &mut [i32], low: usize, high: usize) {
if low < high {
let pi = partition(arr, low, high);
if pi > 0 { quick_sort_helper(arr, low, pi - 1); }
quick_sort_helper(arr, pi + 1, high);
}
}
/// Sorts the array using the Selection Sort algorithm.
///
/// # Arguments
///
/// * `arr` - The array to be sorted.
///
/// # Returns
///
/// The sorted array.
#[pyfunction]
pub fn Selection(mut arr: Vec<i32>) -> PyResult<Vec<i32>> {
let len = arr.len();
for i in 0..len {
let mut min_idx = i;
for j in (i + 1)..len {
if arr[j] < arr[min_idx] {
min_idx = j;
}
}
arr.swap(i, min_idx);
}
Ok(arr)
}
/// Sorts the array using the Insertion Sort algorithm.
///
/// # Arguments
///
/// * `arr` - The array to be sorted.
///
/// # Returns
///
/// The sorted array.
#[pyfunction]
pub fn Insertion(mut arr: Vec<i32>) -> PyResult<Vec<i32>> {
let len = arr.len();
for i in 1..len {
let key = arr[i];
let mut j = i as isize - 1;
while j >= 0 && arr[j as usize] > key {
arr[(j + 1) as usize] = arr[j as usize];
j -= 1;
}
arr[(j + 1) as usize] = key;
}
Ok(arr)
}
/// Sorts the array using the Shell Sort algorithm.
///
/// # Arguments
///
/// * `arr` - The array to be sorted.
///
/// # Returns
///
/// The sorted array.
#[pyfunction]
pub fn Shell(mut arr: Vec<i32>) -> PyResult<Vec<i32>> {
let n = arr.len();
let mut gap = n / 2;
while gap > 0 {
for i in gap..n {
let temp = arr[i];
let mut j = i;
while j >= gap && arr[j - gap] > temp {
arr[j] = arr[j - gap];
j -= gap;
}
arr[j] = temp;
}
gap /= 2;
}
Ok(arr)
}
/// Sorts the array using the Quick Sort algorithm.
///
/// # Arguments
///
/// * `arr` - The array to be sorted.
///
/// # Returns
///
/// The sorted array.
#[pyfunction]
pub fn Quick(mut arr: Vec<i32>) -> PyResult<Vec<i32>> {
let len = arr.len();
if len > 1 {
quick_sort_helper(&mut arr, 0, len - 1);
}
Ok(arr)
}
/// Sorts the array using the Merge Sort algorithm.
///
/// # Arguments
///
/// * `arr` - The array to be sorted.
///
/// # Returns
///
/// The sorted array.
#[pyfunction]
pub fn Merge(mut arr: Vec<i32>) -> PyResult<Vec<i32>> {
let len = arr.len();
if len > 1 {
merge_sort_helper(&mut arr, 0, len - 1);
}
Ok(arr)
}
/// Sorts a list of integers using LSD (Least Significant Digit) Radix Sort.
///
/// # Arguments
///
/// * `arr` - The vector of integers to be sorted.
///
/// # Returns
///
/// A sorted vector of integers.
///
#[pyfunction]
pub fn LsdRadix(mut arr: Vec<u32>) -> PyResult<Vec<u32>> {
if arr.is_empty() {
return Ok(arr);
}
let max_value = *arr.iter().max().unwrap_or(&0);
let mut exp = 1;
let mut output = vec![0; arr.len()];
while exp <= max_value {
let mut count = vec![0; 10];
for &num in &arr {
count[((num / exp) % 10) as usize] += 1;
}
for i in 1..10 {
count[i] += count[i - 1];
}
for i in (0..arr.len()).rev() {
let digit = ((arr[i] / exp) % 10) as usize;
output[count[digit] - 1] = arr[i];
count[digit] -= 1;
}
for i in 0..arr.len() {
arr[i] = output[i];
}
exp *= 10;
}
Ok(arr)
}
/// Perform MSD Radix Sort on a list of strings.
///
/// This function implements the Most Significant Digit (MSD) Radix Sort algorithm
/// to sort a list of strings in lexicographic order.
///
/// Args:
/// strings (List[str]): A list of strings to be sorted.
///
/// Returns:
/// List[str]: A new list containing the input strings in sorted order.
///
/// Example:
/// >>> msd_radix_sort(["cat", "dog", "bird", "ant"])
/// ["ant", "bird", "cat", "dog"]
#[pyfunction]
pub fn MsdRadix(strings: &PyList) -> PyResult<Vec<String>> {
let mut vec: Vec<String> = strings.extract()?;
if vec.is_empty() {
return Ok(vec);
}
let len = vec.len();
let max_len = vec.iter().map(|s| s.len()).max().unwrap();
msd_radix_sort_helper(&mut vec, 0, len, 0, max_len);
Ok(vec)
}
/// Helper function for MSD Radix Sort.
///
/// This recursive function performs the actual sorting of a subset of the strings.
///
/// Args:
/// vec: Mutable reference to the vector of strings being sorted.
/// lo: Starting index of the current subset.
/// hi: Ending index (exclusive) of the current subset.
/// d: Current digit (character position) being examined.
/// max_len: Maximum length of any string in the original input.
fn msd_radix_sort_helper(vec: &mut [String], lo: usize, hi: usize, d: usize, max_len: usize) {
if hi <= lo + 1 || d >= max_len {
return;
}
let r = 256; // Assuming ASCII characters
let mut count = vec![0; r + 2];
// Compute frequency counts
for i in lo..hi {
count[char_at(&vec[i], d) + 2] += 1;
}
// Transform counts to indices
for i in 0..r + 1 {
count[i + 1] += count[i];
}
// Distribute
let mut aux = vec![String::new(); hi - lo];
for i in lo..hi {
let c = char_at(&vec[i], d);
aux[count[c + 1]] = vec[i].clone();
count[c + 1] += 1;
}
// Copy back
for i in lo..hi {
vec[i] = aux[i - lo].clone();
}
// Recursively sort for each character
for i in 0..r {
msd_radix_sort_helper(vec, lo + count[i], lo + count[i + 1], d + 1, max_len);
}
}
/// Get the character at a specific index in a string.
///
/// If the index is out of bounds, return -1.
///
/// Args:
/// s: Reference to the string.
/// d: Index of the character to retrieve.
///
/// Returns:
/// usize: ASCII value of the character, or -1 if out of bounds.
fn char_at(s: &str, d: usize) -> usize {
if d < s.len() {
s.as_bytes()[d] as usize
} else {
0
}
}
/// Sorts a list of strings using 3-way Radix Quicksort.
///
/// # Arguments
///
/// * `arr_py` - Python list of strings to be sorted.
///
/// # Returns
///
/// A sorted vector of strings.
///
/// # Examples
///
/// ```
/// # use radix_quicksort::radix_quicksort;
/// # use pyo3::types::PyList;
/// # use pyo3::Python;
/// let gil = Python::acquire_gil();
/// let py = gil.python();
/// let arr_py = PyList::new(py, &["bc", "ab", "aa", "cb", "ac", "ca", "bb", "ba"]).unwrap();
/// let sorted_arr = radix_quicksort(arr_py).unwrap();
/// assert_eq!(sorted_arr, vec!["aa", "ab", "ac", "ba", "bb", "bc", "ca", "cb"]);
/// ```
#[pyfunction]
pub fn RadixQuicksort(arr_py: &PyList) -> PyResult<Vec<&str>> {
let mut arr: Vec<&str> = Vec::new();
for item in arr_py.iter() {
let s = item.extract::<&str>()?;
arr.push(s);
}
if arr.is_empty() {
return Ok(arr);
}
let mut output = vec![String::new(); arr.len()];
let len = arr.len();
radix_quicksort_helper(&mut arr, &mut output, 0, len - 1, 0);
Ok(arr)
}
fn radix_quicksort_helper(arr: &mut [&str], output: &mut [String], left: usize, right: usize, d: usize) {
if left >= right || d >= arr[0].len() {
return;
}
let mut lo = left;
let mut hi = right;
let pivot = get_char(arr[left], d);
let mut i = left + 1;
while i <= hi {
let curr = get_char(arr[i], d);
if curr < pivot {
arr.swap(lo, i);
lo += 1;
i += 1;
} else if curr > pivot {
arr.swap(i, hi);
if hi > 0 {
hi -= 1;
}
} else {
i += 1;
}
}
radix_quicksort_helper(arr, output, left, lo - 1, d);
if pivot != '\0' {
radix_quicksort_helper(arr, output, lo, hi, d + 1);
}
radix_quicksort_helper(arr, output, hi + 1, right, d);
}
fn get_char(s: &str, d: usize) -> char {
if d < s.len() {
s.chars().nth(d).unwrap_or('\0')
} else {
'\0'
}
}