题解 | #计算某字母出现次数#

#include<iostream>
#include<map>
using namespace std;
map<char, int> char2num;
int main(){
    char a;
    char c;
    for(int i=0;i<500;i++){
        cin.get(c);
        if (c == '\n')
            break;
        else if(c <= 'Z' && c >= 'A'){
            if(char2num.find(c) == char2num.end())
                char2num[c] = 1;
            else
                char2num[c] ++;
        }
        else if(c <= 'z' && c >= 'a'){
            if(char2num.find(c-32) == char2num.end())
                char2num[c-32] = 1;
            else
                char2num[c-32] ++;
        }else{}
    }
    cin>>a;
    if(a <= 'Z' && a >= 'A'){
        // 大写
        if(char2num.find(a) != char2num.end()){
            cout<<char2num[a];
        }else
            cout<<0;
    }else{
        // 小写
        if(char2num.find(a-32) != char2num.end()){
            cout<<char2num[a]+char2num[a-32];
        }else
            cout<<0;
    }
    return 0;
}