Not optimal but accepted solution for problem 5 - longest palindromic substring

5-longest-palindromic-substring.cpp

@@ -0,0 +1,54 @@
+#include <string>
+using std::string;
+
+class LongestPalindromicSubstringSolution {
+public:
+    string longestPalindrome(string s) {
+
+        if (s.length() == 1)
+            return s;
+        if (s.length() == 2) {
+            if (s[0] == s[1])
+                return s;
+
+            char str[2];
+            str[0] = s[0];
+            str[1] = 0;
+            return str;
+        }
+
+        const char* ptrStart = s.c_str();
+        const unsigned long strLen = s.length();
+        unsigned long strLongest = strLen;
+        char *res = new char[strLen+1];
+        memset(res, 0, strLen+1);
+
+        for (; strLongest >= 2; strLongest--) {
+            for (unsigned long i = 0; (i + strLongest) <= strLen; i++) {
+                const char* start(ptrStart + i);
+                const char* finish(start + strLongest - 1);
+
+                while (start <= finish) {
+                    if (*start != *finish) break;
+                    start++;
+                    finish--;
+                }
+
+                if (start > finish) {
+                    memcpy(res, ptrStart + i, strLongest);
+                    break;
+                }
+            }
+            if (res[0] != 0) break;
+        }
+
+        if (res[0] == 0) {
+            res[0] = s[0];
+        }
+
+        string resStr(res);
+        delete [] res;
+
+        return resStr;
+    }
+};