HW3A

#include <iostream>
#include <vector>
#include <utility>
#include <algorithm>

using namespace std;

int main()
{
    int i = 0;
    vector <pair<int, char>> L(26);
    for (i = 0; i < 26; i++) L[i].first = 0;
    for (i = 0; i < 26; i++) L[i].second = (char)((int)'A' + i);

    char c;
    for (int c = getchar(); c != EOF; c = getchar()) {
        if ((c >= 'A') && (c <= 'Z')) L[(int)(c)-(int)('A')].first++;
    }

    sort(L.begin(), L.end(), [](pair<int, char> a, pair<int, char> b) {return a.first > b.first; });
    for (i = 0; i < 26; i++) if (L[i].first) cout << L[i].second << ' ' << L[i].first << endl;
}