Add 125_Valid_Palindrome.cpp

C++/125_Valid_Palindrome.cpp

@@ -0,0 +1,38 @@
+//125. Valid Palindrome
+/*Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.
+
+For example,
+"A man, a plan, a canal: Panama" is a palindrome.
+"race a car" is not a palindrome.
+
+Author: Xinyu Liu
+*/
+
+#include <string>
+using namespace std;
+
+class Solution {
+public:
+    bool isPalindrome(string s) {
+        string::iterator start = s.begin();
+        string::iterator end = s.end() - 1;
+        while(start < end){
+            while (start < end && !isalnum(*start))
+                start ++;
+            while (start < end && !isalnum(*end))
+                end --;       
+            if (tolower(*start )!= tolower(*end))
+                return false;
+            start ++;
+            end--;
+        }
+         return true;
+
+    }
+};
+
+void main(){
+    string str_test = "test";
+    Solution sol;
+    bool bol = sol.isPalindrome(str_test);
+}