leetcode new problems

leetcode/lc5/ExpandCentre.cpp

@@ -1,17 +1,18 @@
+
 class Solution {
 public:
         string longestPalindrome(string s) {
         if (s.length() <= 1) {
             return s;
-        }
+        }
 
         auto expand_from_center = [&](int left, int right) {
             while (left >= 0 && right < s.length() && s[left] == s[right]) {
                 left--;
                 right++;
-            }
+            }
             return s.substr(left + 1, right - left - 1);
-        };
+        };
 
         string max_str = s.substr(0, 1);
 
@@ -28,5 +29,39 @@ public:
         }
 
         return max_str;
-    }
-};
+    }
+};
+
+class Solution {
+public:
+    std::string longestPalindrome(std::string s) {
+        if (s.length() <= 1) {
+            return s;
+        }
+
+        auto expand_from_center = [&](int left, int right) {
+            while (left >= 0 && right < s.length() && s[left] == s[right]) {
+                left--;
+                right++;
+            }
+            return s.substr(left + 1, right - left - 1);
+        };
+
+        std::string max_str = s.substr(0, 1);
+
+        for (int i = 0; i < s.length() - 1; i++) {
+            std::string odd = expand_from_center(i, i);
+            std::string even = expand_from_center(i, i + 1);
+
+            if (odd.length() > max_str.length()) {
+                max_str = odd;
+            }
+            if (even.length() > max_str.length()) {
+                max_str = even;
+            }
+        }
+
+        return max_str;
+    }
+};
+