problem_008.rs

// -*- compile-command: "rustc -o problem_008_rs problem_008.rs" -*-
// Copyright (c) 2016 Michael Caldwell

fn main() {
    let num = "7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450";

    println!("Project Euler - Problem 8");
    println!("Find the thirteen adjacent digits in the 1000-digit number that have the greatest product. What is the value of this product?\n\n{}\n", num);

    let mut greatest:u64 = 0;

    for i in 0..1000-13 {
        let mut value:u64 = 1;
        let string = &num[i..i+13];
        for c in string.chars() {
            value *= c.to_digit(10).unwrap() as u64;
        }
        if value > greatest {
            greatest = value;
        }
    }

    println!("{}", greatest);
}