palindrome_number.cpp

Author: jakoo

palindrome_number.cpp

@@ -0,0 +1,33 @@
+class Solution {
+public:
+    bool isPalindrome(int x) {
+        if (x < 0)
+            return false;
+        if (x == 0)
+            return true;
+            
+        int k = getNumDigit(x);
+        
+        for (int i = 1, j = k; i < j; ++i, --j)
+        {
+            if (getKthNum(x, i) != getKthNum(x, j))
+                return false;
+        }
+        
+        return true;
+    }
+    int getNumDigit(int x)
+    {
+        int k = 1;
+        while (x /= 10) ++k;
+        return k;
+    }
+    int getKthNum(int x, int k)
+    {
+        if (k == 1)
+            return x % 10;
+
+        long mask = pow(10, k);
+        return (x % mask - x % (mask / 10)) / (mask / 10);
+    }
+};