initial

.gitignore

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+/target

Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "qr-random"
+version = "0.1.0"

Cargo.toml

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+[package]
+name = "qr-random"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]

src/main.rs

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+use std::env;
+
+fn main() {
+    // try 48413
+    let s: usize = env::args()
+        .nth(1)
+        .expect("give me a number")
+        .parse()
+        .unwrap();
+
+    let p = 2 * s + 1;
+    let mut qr = vec![false; p];
+    for n in 1..p {
+        qr[(n * n) % p] = true;
+    }
+
+    for is_qr in qr {
+        let color_code: u8 = if is_qr { 255 } else { 232 };
+        print!("\x1b[48;5;{color_code}m  ");
+    }
+
+    print!("\x1b[0m");
+}