409. Longest Palindrome

class Solution { private: bool static compare(int a,int b) { return a>b; } public: int longestPalindrome(string s) { map<char ,int > m; for(int i=0;i<s.size();i++) { m[s[i]]++; } int rest=0; vector<int> v; for(map<char,int>::iterator it=m.begin();it!=m.end();it++) { if(it->second%2==0) { rest+=it->second; } else { v.push_back(it->second); } } sort(v.begin(),v.end(),compare); if(v.size()>0) { rest+=v[0]; } for(int i=1;i<v.size();i++) { if(v[i]>1) rest+=(v[i]-1); else break; } return rest; } };