2024-08-24 find-the-closest-palindrome

AlgoLeadMe · Aug 25, 2024 · 7517dc6 · 7517dc6
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diff --git a/InSange/README.md b/InSange/README.md
@@ -30,6 +30,8 @@
 | 26차시 | 2024.08.11 |  수학  | [Magic Squares In Grid](https://leetcode.com/problems/magic-squares-in-grid/)  | [#26](https://github.com/AlgoLeadMe/AlgoLeadMe-8/pull/89)]
 | 27차시 | 2024.08.17 |  문자열  | [Number of Senior Citizens](https://leetcode.com/problems/number-of-senior-citizens/)  | [#27](https://github.com/AlgoLeadMe/AlgoLeadMe-8/pull/91)]
 | 28차시 | 2024.08.21 |  백트래킹 | [월드컵](https://www.acmicpc.net/problem/6987)  | [#28](https://github.com/AlgoLeadMe/AlgoLeadMe-8/pull/94)]
+| 29차시 | 2024.08.25 |  문자열 | [Find the Closest Palindrome](https://leetcode.com/problems/find-the-closest-palindrome/)  | [#29](https://github.com/AlgoLeadMe/AlgoLeadMe-8/pull/98)]
 ---
 
 https://leetcode.com/problems/robot-collisions/
+Find the Closest Palindrome
diff --git a/InSange/문자열/564_Find the Closest Palindrome.cpp b/InSange/문자열/564_Find the Closest Palindrome.cpp
@@ -0,0 +1,74 @@
+#include <iostream>
+#include <string>
+
+using namespace std;
+
+class Solution {
+public:
+    long long Convert(long long& num)
+    {
+        string s = to_string(num);
+        int n = s.length();
+        int l = (n - 1) / 2;
+        int r = n / 2;
+        while (l >= 0) s[r++] = s[l--];
+        return stoll(s);
+    }
+
+    long long UpPal(long long num)
+    {
+        long long left = 0;
+        long long right = num;
+        long long ans = INT_MIN;
+
+        while (left <= right)
+        {
+            long long mid = (right + left) / 2;
+            long long palin = Convert(mid);
+            if (palin < num)
+            {
+                ans = palin;
+                left = mid + 1;
+            }
+            else
+            {
+                right = mid - 1;
+            }
+        }
+
+        return ans;
+    }
+
+    long long DownPal(long long num)
+    {
+        long long left = num;
+        long long right = 1e18;
+        long long ans = INT_MIN;
+
+        while (left <= right) {
+            long long mid = (right + left) / 2;
+            long long palin = Convert(mid);
+            if (palin > num)
+            {
+                ans = palin;
+                right = mid - 1;
+            }
+            else
+            {
+                left = mid + 1;
+            }
+        }
+
+        return ans;
+    }
+
+    string nearestPalindromic(string n) {
+        long long num = stoll(n);
+        long long a = UpPal(num);
+        long long b = DownPal(num);
+
+        if (abs(a - num) <= abs(b - num)) return to_string(a);
+
+        return to_string(b);
+    }
+};