Merge Sort in Rust

Welcome to the Merge Sort in Rust page! Here, you'll find the source code for this program as well as a description of how the program works.

Current Solution

use std::env::args;
use std::process::exit;
use std::str::FromStr;

fn usage() -> ! {
    println!("Usage: please provide a list of at least two integers to sort in the format \"1, 2, 3, 4, 5\"");
    exit(0);
}

fn parse_int<T: FromStr>(s: &str) -> Result<T, <T as FromStr>::Err> {
    s.trim().parse::<T>()
}

fn parse_int_list<T: FromStr>(s: &str) -> Result<Vec<T>, <T as FromStr>::Err> {
    s.split(',')
        .map(parse_int)
        .collect::<Result<Vec<T>, <T as FromStr>::Err>>()
}

fn merge<T: PartialOrd + Copy>(lhs: &Vec<T>, rhs: &Vec<T>, merged_arr: &mut Vec<T>) {
    let mut lhs_idx = 0;
    let mut rhs_idx = 0;
    let mut merged_idx = 0;

    while lhs_idx < lhs.len() && rhs_idx < rhs.len() {
        if lhs[lhs_idx] < rhs[rhs_idx] {
            merged_arr[merged_idx] = lhs[lhs_idx];
            lhs_idx += 1;
        } else {
            merged_arr[merged_idx] = rhs[rhs_idx];
            rhs_idx += 1;
        }

        merged_idx += 1;
    }

    if lhs_idx < lhs.len() {
        merged_arr[merged_idx..].copy_from_slice(&lhs[lhs_idx..]);
    }
    else if rhs_idx < rhs.len() {
        merged_arr[merged_idx..].copy_from_slice(&rhs[rhs_idx..]);
    }
}

fn merge_sort<T: PartialOrd + Copy>(arr: &mut Vec<T>) {
    if arr.len() <= 1 {
        return;
    }

    let mid = arr.len() / 2;
    let mut lhs = arr[..mid].to_vec();
    let mut rhs = arr[mid..].to_vec();

    merge_sort(&mut lhs);
    merge_sort(&mut rhs);

    merge(&lhs, &rhs, arr);
}

fn main() {
    let mut args = args().skip(1);

    // Convert 1st command-line argument to list of integers
    let mut arr: Vec<i32> = args
        .next()
        .and_then(|s| parse_int_list(&s).ok())
        .unwrap_or_else(|| usage());

    // Exit if list too small
    if arr.len() < 2 {
        usage();
    }

    merge_sort::<i32>(&mut arr);
    println!("{arr:?}");
}

Merge Sort in Rust was written by:

• Andrew Johnson
• rzuckerm

If you see anything you'd like to change or update, please consider contributing.

Note: The solution shown above is the current solution in the Sample Programs repository as of May 08 2023 19:53:07. The solution was first committed on Oct 03 2020 19:42:59. As a result, documentation below may be outdated.

How to Implement the Solution

No 'How to Implement the Solution' section available. Please consider contributing.

How to Run the Solution

No 'How to Run the Solution' section available. Please consider contributing.