开始想的简单了，确实没想到奇数字母删去一个后也能用

解法：

桶排序

#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;
#define endl '\n'
#define int long long
signed main() {int t;cin >> t;while (t--) {string s;cin >> s;vector<int> tong(26, 0);for (int i = 0; i < s.size(); i++) tong[s[i] - 'a']++;int flag = 0;long long sum = 0;for (int i = 0; i < 26; i++) {if (tong[i] & 1) {if (!flag) {sum += tong[i];flag = 1;}else {sum += tong[i] - 1;}}else {sum += tong[i];}}cout << sum  << endl;}return 0;
}