RT

#include <bits/stdc++.h>
using namespace std;
int main(){
    string s;
    getline(cin, s);
    string tmp = "";
    int maxlen = -1000000, minlen = 100000000;
    string maxs = "", mins = "";
    for (int i = 0; i <= s.size() - 1; i++){
        if (s[i] != ' ' && s[i] != ',' && s[i] != '.') tmp += s[i];
        else{
            if (tmp.size() - 1 > maxlen)
            {
                maxlen = tmp.size() - 1;
                maxs = tmp;
            }
            if (tmp.size() - 1 < minlen)
            {
                minlen = tmp.size() - 1;
                mins = tmp;
            }
            tmp = "";
        }
    }
    cout << maxs << "\n" << mins << endl;
    return 0;
}

可以输出长度最小的字符串，但输出不了长度最大的。

help.