2026/05/13

[LeetCode] 409 Longest Palindrome 

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class Solution {
public:
  int longestPalindrome(string s) {
    std::unordered_map<char, int> cntMap;
    for (auto c : s)
      cntMap[c]++;
    int len = 0;
    bool hasOdd = false;
    for (auto &entry : cntMap) {
      int cnt = entry.second;
      if (cnt % 2 == 0)
        len += cnt;
      else {
        len += cnt - 1;
        hasOdd = true;
      }
    }
    if (hasOdd)
      len++;
    return len;
  }
};
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