solve aylei#9

Author: aylei

Diff for: src/n0009_palindrome_number.rs

@@ -1,6 +1,6 @@
-/**
- * [9] Palindrome Number
- *
+/**
+ * [9] Palindrome Number
+ *
  * Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward.
  * 
  * Example 1:
@@ -29,25 +29,52 @@
  * Follow up:
  * 
  * Coud you solve it without converting the integer to a string?
- * 
- */
-pub struct Solution {}
-
-// submission codes start here
-
-impl Solution {
-    pub fn is_palindrome(x: i32) -> bool {
-        
-    }
-}
-
-// submission codes end
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn test_9() {
-    }
-}
+ * 
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+// not optimal, we only have to revert half of the string
+impl Solution {
+    pub fn is_palindrome(x: i32) -> bool {
+        if x < 0 { return false }
+        let mut digits: Vec<i32> = Vec::new();
+        let mut input = x;
+        while input != 0 {
+            digits.push(input % 10);
+            input = input / 10;
+        }
+        let len = digits.len();
+        // handle one digit
+        if len < 2 { return true }
+        // handle end with 0
+        if digits[0] == 0 { return false }
+        let mut i = 0;
+        while i < len / 2 {
+            if digits[i] != digits[len - 1 - i] {
+                return false
+            }
+            i += 1;
+        }
+        true
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_9() {
+        assert_eq!(Solution::is_palindrome(-32), false);
+        assert_eq!(Solution::is_palindrome(10), false);
+        assert_eq!(Solution::is_palindrome(0), true);
+        assert_eq!(Solution::is_palindrome(9), true);
+        assert_eq!(Solution::is_palindrome(121), true);
+        assert_eq!(Solution::is_palindrome(2222), true);
+        assert_eq!(Solution::is_palindrome(11222211), true);
+    }
+}