【題解】ZeroJudge d267: 11577 – Letter Frequency

#include <iostream>
#include <map>
using namespace std;
  
int main() {
    int T;
    cin >> T;
    string s;
    getline(cin, s); //混用cin與getline，先清除cin之後的緩衝區
    while (T--) {
        getline(cin, s);
        int a[26] = {}; //大小寫字母不分
        int mx = 0;
        for (int i = 0; i < s.size(); i++) {
            int idx = -1;
            if (s[i] >= 'A' and s[i] <= 'Z') {
                idx = s[i] - 'A';
            }
            if (s[i] >= 'a' and s[i] <= 'z') {
                idx = s[i] - 'a';
            }
            if (idx >= 0) {
                a[idx]++;
                mx = max(mx, a[idx]);
            }
        }
        for (int i = 0; i < 26; i++) {
            if (a[i] == mx) {
                cout << (char)('a' + i);
            }
        }
        cout << "\n";
    }
    return 0;
}

#include <iostream>
#include <map>
using namespace std;
 
int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int n;
    string s;
    cin >> n;
    getline(cin, s);
    while (n--){
        getline(cin, s);
        map<char,int> mp;
        int mx = 0;
        for (int i = 0; i < s.size(); i++){
            if (s[i] >= 'a' && s[i] <= 'z'){
                mp[s[i]]++;
                mx = max(mx, mp[s[i]]);
            } else if (s[i] >= 'A' && s[i] <= 'Z'){
                s[i] = 'a' + (s[i] - 'A');
                mp[s[i]]++;
                mx = max(mx, mp[s[i]]);
            }
        }
        for (auto i: mp){
            if (i.second == mx){
                cout << i.first;
            }
        }
        cout << "\n";
    }
    return 0;
}

n = int(input())
for i in range(n):
    s = input()
    dic = {}
    for c in s:
        if not c.isalpha():
            continue
        c = c.lower()
        dic[c] = dic.get(c, 0) + 1
    mx = max(dic.values())
    for c in sorted(dic.keys()):
        if dic[c] == mx:
            print(c, end="")
    print()