Time: 4 ms (84.11%), Space: 7.6 MB (75.42%) - LeetHub

Author: karygauss03

0214-shortest-palindrome/0214-shortest-palindrome.cpp

@@ -0,0 +1,29 @@
+class Solution {
+private:
+    bool pal(string s, int i, int j){
+        for(; i < j; i++, j--){
+            if(s[i] != s[j])
+                return 0;
+        }
+        return 1;
+    }
+public:
+    string shortestPalindrome(string s) {
+        int n = s.size();
+        vector<int> v(n + 1, 0);
+        for (int i = 1 ; i <= n ; i++){
+            v[i] += v[i - 1] + (s[i - 1] - 'a');
+        }
+        string ans;
+        for (int i = n ; i >= 1 ; i--){
+            if((i % 2 == 0 && v[i/2] == v[i] - v[i/2]) || (i % 2 != 0 && v[i/2] == v[i] - v[i/2 + 1])){
+                if(pal(s,0,i-1)){
+                    ans = s.substr(i);
+                    reverse(ans.begin(), ans.end());
+                    break;
+                }
+            }
+        }
+        return ans + s;
+    }
+};