Run Rust 1 online

What's in Rust 1

• Ownership + borrowing, no garbage collector, C-adjacent performance.
• The 2024 edition is the current default: `let-else`, dyn-safe trait objects tightened, gen blocks (preview).
• Stable async/await; std::process, std::thread, and the whole cross-platform stdlib.

What you get in Rust 1

Clicking "Run now" opens the playground with this exact code and a matching test case — passes on first Run.

use std::io;
fn main() {
    let mut s = String::new();
    io::stdin().read_line(&mut s).unwrap();
    let n: i64 = s.trim().parse().unwrap();
    println!("{}", n * 2);
}

How ls-judge runs Rust 1

Every submission is compiled and executed inside its own Firecracker microVM — the same isolation primitive AWS Lambda uses. No shared container, no shared kernel with other users' code. The Rust 1toolchain shipped with the microVM is the real thing (not a browser-side emulation): syscalls behave the way they do in production, and the compile / runtime behaviour matches what you would see on your own machine with that version installed.

Feed stdin from the Tests panel, watch verdicts stream per test case over a WebSocket. Free to use, no sign-up, works from any browser.