Watermelon

I’ve recently learned about Competitive Programming and started solving problems...

I hope this isn’t just a phase.

Introduction

Problem Statement

So Pete and his friend Billy have various watermelons and would like to know if it’s possible to evenly divide the watermelon into 2 even numbers.

So in this example, the answer would be yes because you can divide the 8 kilo watermelon into a part that is 2 kilos and another that is 6 kilos.

Concept

Since the only stipulation is that both parts need to be even numbers, and every even number is divisible by 2. We could just determine if the original watermelon is even.

Implementation

We can start with some boilerplate where we recieve input...

use std::io::stdin;

fn main() -> Result<(), String> {
    let mut input = String::new();
    
    let _ = stdin().read_line(&mut input);

    Ok(())
}

Now we just need to get parse the input into a usable type...

use std::io::stdin;

fn main() -> Result<(), String> {
    let mut input = String::new();
    
    let _ = stdin().read_line(&mut input);
    // #1
    let number =  input.trim()
                       .parse::<i32>()
                       .unwrap();

    Ok(())
}

Let’s break this down. So we take the input and assign it to the number variable, but before then we...

“Trim()”: We remove the newline character from the input string.

“Parse()”: We then take the input string and parse it to a 32 bit integer.

“Unwrap()”: The result of the parsing produces the value we want, but it’s wrapped in a “Error-handling object” (for a lack of a better term). We must call this function to unwrap the object and retrieve the value we want.

So now we move on to the logic of the program. Here, we can use conditionals. If the number is even, then print “YES”. If the number is not even, then print “NO”.

We can implement this like...

use std::io::stdin;

fn main() -> Result<(), String> {
//  <--snip-->
    if number % 2 == 0 { println!("YES"); }
    else { println!("NO"); }
//  <--snip-->
}

And that’s pretty much it!

Full Code Solution

use std::io::stdin;

fn main() -> Result<(), String> {
    let mut input = String::new();
    
    let _ = stdin().read_line(&mut input);
    
    let number =  input.trim()
                       .parse::<i32>()
                       .unwrap();

    if number % 2 == 0 { println!("YES"); }
    else { println!("NO"); }

    Ok(())
}