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;
}