solution
潜在的非法字符里可能包含空格,所以不能直接用cin接收string(测试点2)
#include<iostream>
#include<string>
using namespace std;
int judge(string s){
if(s.size() < 6) return 1;
int num = 0, c = 0;
for(int i = 0; i < s.size(); i++){
if((s[i] >= 'a' && s[i] <= 'z') || (s[i] >= 'A' && s[i] <= 'Z')) c = 1;
else if(s[i] >= '0' && s[i] <= '9') num = 1;
else if(s[i]