Binary Search in Rust

Welcome to the Binary Search 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 sorted integers (\"1, 4, 5, 11, 12\") and the integer to find (\"11\")");
    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 is_sorted<T: PartialOrd>(arr: &Vec<T>) -> bool {
    (0..(arr.len() - 1))
        .all(|x| arr[x] <= arr[x + 1])
}

fn binary_search<T: PartialOrd + PartialEq>(search_arr: &Vec<T>, target: &T) -> Option<usize> {
    let mut low: usize = 0;
    let mut high: usize = search_arr.len() - 1;

    while low <= high {
        let mid = ((high - low) / 2) + low;
        let val = &search_arr[mid];

        if val == target {
            return Some(mid);
        }

        // If value is < target then search between mid + 1 and high
        if val < target {
            low = mid + 1;
        }

        // If value is > target then search between low and mid - 1
        if val > target {
            high = mid - 1;
        }
    }

    return None;
}

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

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

    // Make sure array is sorted
    if !is_sorted(&arr) {
        usage();
    }

    // Convert 2nd command-line argument to integer
    let target: i32 = args
        .next()
        .and_then(|s| parse_int(&s).ok())
        .unwrap_or_else(|| usage());

    match binary_search::<i32>(&arr, &target) {
        Some(_) => println!("true"),
        None => println!("false"),
    }
}

Binary Search in Rust was written by:

• Andrew Johnson
• rzuckerm

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

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.