upd

9. Palindrome Number/Solution.java

@@ -0,0 +1,16 @@
+class Solution {
+    public static void main(String[] args) {
+      int test[] = {121, -121, 10};
+
+      for (int t : test) {
+        System.out.println("isPalindrome(" + t + ") = " + isPalindrome(t));
+      }
+    }
+
+    public static boolean isPalindrome(int x) {
+      StringBuilder sb = new StringBuilder(Integer.toString(x));
+      sb.reverse();
+      String reversed = sb.toString();
+      return Integer.toString(x).equals(reversed);
+    }
+}

9. Palindrome Number/solution.c

@@ -0,0 +1,26 @@
+#include <stdlib.h>
+#include <stdbool.h>
+
+bool isPalindrome(int x) {
+    // negatives and numbers ending in 0 (except 0 itself) are not palindromes
+    if (x < 0 || (x % 10 == 0 && x != 0))
+        return false;
+
+    int reversedHalf = 0;
+
+    while (x > reversedHalf) {
+        reversedHalf = reversedHalf * 10 + x % 10;
+        x /= 10;
+    }
+
+    // for even digits: x == reversedHalf
+    // for odd digits:  x == reversedHalf / 10
+    return (x == reversedHalf) || (x == reversedHalf / 10);
+}
+
+
+int main(int argc, char *argv[])
+{
+  return EXIT_SUCCESS;
+}
+

9. Palindrome Number/solution.cpp

@@ -0,0 +1,27 @@
+#include <algorithm>
+#include <iostream>
+#include <string>
+
+
+class Solution {
+public:
+    bool isPalindrome(int x) {
+      std::string s = std::to_string(x);
+      std::string reversed_s = s;
+
+      std::reverse(reversed_s.begin(), reversed_s.end());
+
+      return s == reversed_s;
+    }
+};
+
+int main (int argc, char *argv[]) {
+  Solution s;
+  int test[] = {121, -121, 10};
+
+  for (int t : test) {
+    std::cout << "isPalindrome(" << t << ") = " << s.isPalindrome(t) << std::endl;
+  }
+
+  return 0;
+}

9. Palindrome Number/solution.py

@@ -0,0 +1,13 @@
+class Solution:
+    def isPalindrome(self, x: int) -> bool:
+        return str(x) == str(x)[::-1]
+
+def main() -> None:
+    test = [121, -121, 10]  # True, False, False  
+    s = Solution()
+
+    for t in test:
+        print(f"isPalindrome({t}) = {s.isPalindrome(t)}")
+ 
+if __name__ == "__main__":
+    main()

README.md

@@ -0,0 +1,7 @@
+here i've got some leetcode problems & solutions to them
+
+| **Number** | **Name** | **Difficulty** | **Solution** |
+| ---------- | -------- | -------------- | ------------ |
+| 1 | *Two Sum* | Easy | [text](url) |
+| 9 | *Palindrome Number* | Easy | [text](url) |
+