Time: 0 ms (100.00%), Space: 8.3 MB (77.93%) - LeetHub

Author: knockcat

0564-find-the-closest-palindrome/0564-find-the-closest-palindrome.cpp

@@ -0,0 +1,61 @@
+using ll = long long;
+
+class Solution {
+public:
+    
+    ll palindrome(ll firstHalf, bool isEven)
+    {
+        ll resultNum = firstHalf;
+        
+        if(!isEven)
+            firstHalf /= 10;
+        
+        while(firstHalf > 0)
+        {
+            resultNum = (resultNum * 10) + (firstHalf%10);
+            firstHalf /= 10;
+        }
+        
+        return resultNum;
+    }
+    
+    string nearestPalindromic(string n) {
+        
+        int sz = n.size();
+        int mid = sz/2;
+        
+        ll firstHalfLen = (sz % 2 == 0 ? mid : mid+1);
+        
+        ll firstHalf = stoll(n.substr(0, firstHalfLen));
+        
+        vector<ll> pos;
+        
+        pos.push_back(palindrome(firstHalf, sz % 2 == 0));
+        pos.push_back(palindrome(firstHalf+1, sz % 2 == 0));
+        pos.push_back(palindrome(firstHalf-1, sz % 2 == 0));
+        pos.push_back(pow(10, sz-1) - 1);
+        pos.push_back(pow(10, sz) + 1);
+        
+        ll diff = LONG_MAX;
+        ll res = LONG_MAX;
+        ll orgNum = stoll(n);
+        
+        for(auto& num : pos)
+        {
+            if(num == orgNum) continue;
+            
+            if(abs(num - orgNum) < diff)
+            {
+                diff = abs(num - orgNum);
+                res = num;
+            }
+            else if(abs(num - orgNum) == diff)
+            {
+                res = min(res, num);
+            }
+        }
+        
+        return to_string(res);
+        
+    }
+};