Palindrome number

leetcode/src/problems.rs

@@ -2,6 +2,7 @@ pub mod add_two_numbers;
 pub mod longest_palindromic_substring;
 pub mod longest_substring;
 pub mod median_of_two_sorted_arrays;
+pub mod palindrome_number;
 pub mod reverse_integer;
 pub mod string_to_integer;
 pub mod two_sum;

leetcode/src/problems/palindrome_number.rs

@@ -0,0 +1,13 @@
+use super::{Difficulty, Problem, Topic};
+
+pub struct ProblemImpl;
+
+crate::derive_problem!(
+    ProblemImpl,
+    9,
+    Difficulty::Easy,
+    Topic::Algorithms,
+    "Palindrome Number",
+    "Given an integer x, return true if x is a palindrome, and false otherwise.",
+    "Match".into()
+);

leetcode/src/solutions.rs

@@ -4,6 +4,7 @@ pub mod add_two_numbers;
 pub mod longest_palindromic_substring;
 pub mod longest_substring;
 pub mod median_of_two_sorted_arrays;
+pub mod palindrome_number;
 pub mod reverse_integer;
 pub mod string_to_integer;
 pub mod two_sum;

leetcode/src/solutions/palindrome_number.rs

@@ -0,0 +1,63 @@
+use super::Solution;
+
+pub struct SolutionImpl;
+
+impl Solution for SolutionImpl {
+    fn name(&self) -> String {
+        "Solution for Palindrome Number".into()
+    }
+    fn problem_id(&self) -> usize {
+        9
+    }
+    fn location(&self) -> String {
+        crate::location!();
+    }
+    fn test(&self) -> anyhow::Result<()> {
+        let testcases = [(121, true), (-121, false), (10, false)];
+
+        for (x, expect) in testcases {
+            let output = Self::is_palindrome(x);
+
+            if output != expect {
+                anyhow::bail!("test failed for x={x}, output={output}, expect={expect}");
+            }
+        }
+
+        Ok(())
+    }
+    fn benchmark(&self) -> anyhow::Result<usize> {
+        anyhow::bail!("TODO");
+    }
+}
+
+impl SolutionImpl {
+    pub fn is_palindrome(mut x: i32) -> bool {
+        if x < 0 {
+            false
+        } else if x < 10 {
+            true
+        } else {
+            let mut v = Vec::new();
+            while x > 0 {
+                let residue = x % 10;
+                x /= 10;
+
+                v.push(residue);
+            }
+
+            let mut start = 0;
+            let mut end = v.len() - 1;
+
+            while start < end {
+                if v[start] != v[end] {
+                    return false;
+                }
+
+                start += 1;
+                end -= 1;
+            }
+
+            true
+        }
+    }
+}

runtime/src/registration.rs

@@ -29,5 +29,8 @@ pub fn register_all(handle: ContainerHandle) -> anyhow::Result<()> {
     handle.register_problem(|_| problems::string_to_integer::ProblemImpl)?;
     handle.register_solution(|_| solutions::string_to_integer::SolutionImpl)?;
 
+    handle.register_problem(|_| problems::palindrome_number::ProblemImpl)?;
+    handle.register_solution(|_| solutions::palindrome_number::SolutionImpl)?;
+
     Ok(())
 }