1084 Broken Keyboard (20 分)【简单 / 模拟】

https://pintia.cn/problem-sets/994805342720868352/problems/994805382902300672

#include<bits/stdc++.h>
using namespace std;
string a,b,ans;
map<char,int>mp;
int main(void)
{
    
    
    cin>>a>>b;
    for(int i=0;i<b.size();i++) mp[toupper(b[i])]++;
    for(int i=0;i<a.size();i++) if(!mp[toupper(a[i])]) ans+=toupper(a[i]),mp[toupper(a[i])]++;
    cout<<ans;
    return 0;
}