feat: is_prime example

examples/is-prime/program/Cargo.toml

@@ -0,0 +1,8 @@
+[workspace]
+[package]
+version = "0.1.0"
+name = "is-prime-program"
+edition = "2021"
+
+[dependencies]
+sp1-zkvm = { git = "https://github.com/succinctlabs/sp1.git" }

examples/is-prime/program/src/main.rs

@@ -0,0 +1,32 @@
+#![no_main]
+sp1_zkvm::entrypoint!(main);
+
+pub fn main() {
+    let n = sp1_zkvm::io::read::<u64>();
+
+    let is_prime = is_prime(n);
+
+    sp1_zkvm::io::write(&is_prime);
+}
+
+// Returns if divisible via immediate checks than 6k ± 1.
+// Source: https://en.wikipedia.org/wiki/Primality_test#Rust
+fn is_prime(n: u64) -> bool {
+    if n <= 1 {
+        return false;
+    }
+    if n <= 3 {
+        return true;
+    }
+    if n % 2 == 0 || n % 3 == 0 {
+        return false;
+    }
+    let mut i = 5;
+    while i * i <= n {
+        if n % i == 0 || n % (i + 2) == 0 {
+            return false;
+        }
+        i += 6;
+    }
+    true
+}