题解 | #字母统计#

#include<bits/stdc++.h>
using namespace std;

int main() {
    string str;
    getline(cin, str);

    map<char, int> count =
    { //输入的序列中不一定包含所有字母，所以要将所有字母都输入map中
        {'A', 0}, {'B', 0}, {'C', 0}, {'D', 0}, {'E', 0}, {'F', 0}, {'G', 0}, {'H', 0}, {'I', 0}, {'J', 0},
        {'K', 0}, {'L', 0}, {'M', 0}, {'N', 0}, {'O', 0}, {'P', 0}, {'Q', 0}, {'R', 0}, {'S', 0}, {'T', 0},
        {'U', 0}, {'V', 0}, {'W', 0}, {'X', 0}, {'Y', 0}, {'Z', 0}
    };

    //遍历输入的字符串统计各个字母出现的次数
    for (char c : str) {
        if (isalpha(c)) {
            count[c]++;
        }
    }

    //将统计结果输出
    for (auto iter = count.begin(); iter != count.end(); iter++) {
        cout << iter->first << ":" << iter->second << endl;
    }
}