add initial data

palindrome-number/Cargo.lock

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

palindrome-number/Cargo.toml

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+[package]
+name = "palindrome-number"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]

palindrome-number/src/main.rs

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+fn main() {
+    println!("Hello, world!");
+}
+
+fn is_palindrome(x: i32) -> bool {
+    if x < 0 {
+        return false;
+    }
+
+    let mut original = x;
+    let mut reversed = 0;
+
+    while original > 0 {
+        let digit = original % 10;
+        reversed = reversed * 10 + digit;
+        original /= 10;
+    }
+
+    x == reversed
+}