7 more

CSES - CSES Problem Set/Palindrome_Reorder.cpp

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+//  Palindrome Reorder
+
+#include<bits/stdc++.h>
+
+using namespace std;
+
+int main() {
+    map<char, int> char_to_count;
+    string s; cin >> s;
+    for (auto c: s) char_to_count[c]++;
+    string forward;
+    char middle = ' ';
+    for (auto &[ch, c]: char_to_count) {
+        if (c & 1) {
+            if (middle != ' ') {
+                cout << "NO SOLUTION" << endl;
+                return 0;
+            }
+            middle = ch;
+            forward.append(string((c - 1) / 2, ch));
+        } else {
+            forward.append(string(c/2, ch));
+        }
+    }
+
+    cout << forward;
+    if (middle != ' ') cout << middle;
+    std::reverse(forward.begin(), forward.end());
+    cout << forward << endl;
+    return 0;
+}