add c++ solution for 9

fishercoder1534 · fishercoder1534 · commit 3a546a336df1 · 2019-03-23T09:04:40.000-07:00
diff --git a/README.md b/README.md
@@ -757,7 +757,7 @@ Your ideas/fixes/algorithms are more than welcome!
 |12|[Integer to Roman](https://leetcode.com/problems/integer-to-roman/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_12.java)|O(1)|O(1)||Medium| Math, String
 |11|[Container With Most Water](https://leetcode.com/problems/container-with-most-water/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_11.java)|O(n)|O(1)||Medium|
 |10|[Regular Expression Matching](https://leetcode.com/problems/regular-expression-matching/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_10.java)|O(m*n)|O(m*n)||Hard|DP
-|9|[Palindrome Number](https://leetcode.com/problems/palindrome-number/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_9.java)| O(n) | O(1) || Easy
+|9|[Palindrome Number](https://leetcode.com/problems/palindrome-number/)|[Java](../master/src/main/java/com/fishercoder/solutions/_9.java), [C++](../master/cpp/_9.cpp)| O(n) | O(1) || Easy
 |8|[String to Integer (atoi)](https://leetcode.com/problems/string-to-integer-atoi/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_8.java)| O(n) | O(1) | |Medium
 |7|[Reverse Integer](https://leetcode.com/problems/reverse-integer/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_7.java) | O(1) | O(1) | |Easy | 
 |6|[ZigZag Conversion](https://leetcode.com/problems/zigzag-conversion/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_6.java) | O(n) | O(n) | |Easy | 
diff --git a/cpp/_9.cpp b/cpp/_9.cpp
@@ -0,0 +1,60 @@
+/**
+ * 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:
+
+Input: 121
+Output: true
+Example 2:
+
+Input: -121
+Output: false
+Explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome.
+Example 3:
+
+Input: 10
+Output: false
+Explanation: Reads 01 from right to left. Therefore it is not a palindrome.
+Follow up:
+
+Coud you solve it without converting the integer to a string?
+*/
+
+class Solution1 {
+    /**This is a Java translation, while its Java counterpart could be accepted perfectly, this one failed due to
+     * Char 21: runtime error: signed integer overflow: 746384741 * 10 cannot be represented in type 'int' (solution.cpp)
+    */
+public:
+    bool isPalindrome(int x) {
+        if (x == 0) {
+            return true;
+        } else if (x < 0) {
+            return false;
+        }
+        int tmp = x;
+        int reverse = 0;
+        while (tmp != 0) {
+            reverse *= 10;
+            reverse += tmp % 10;
+            tmp /= 10;
+        }
+        return reverse == x;
+    }
+};
+
+class Solution2 {
+public:
+    bool isPalindrome(int x) {
+        if (x < 0 || (x != 0 && x%10 == 0)) {
+            return false;
+        }
+        int sum = 0;
+        while (x > sum) {
+            sum = sum*10 + x%10;
+            x /= 10;
+        }
+        return (x == sum) || (x == sum/10);
+    }
+};
