1.單case很多清空沒必要的

2.string+ char 最好用pushback

3.string +string就直接+

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

const int N=2e6+10;
map<string, int> mp;

string temp,res;
int num;
string s;
int n;

bool Judge(char x)
{
  if(x>='0'&&x<='9') return true;
  if(x>='A'&&x<='Z') return true;
  if(x>='a'&&x<='z') return true;
  return false;
}

int main()
{
  getline(cin,s);
  n=s.length();
  bool flag = true;
  int ans=0;
  //mp.clear();
  temp = "";
  for(int i=0;i<n;i++)
  {
    if(s[i]>='A'&&s[i]<='Z')
      s[i] = s[i] + 'a' - 'A';
    if(Judge(s[i]))
    {
      temp.push_back(s[i]);//temp = temp + s[i];
      flag=true;
    }
    else
    {
      num = temp.length();
      if(num)
      {
        mp[temp]++;
        if(mp[temp]>ans)
        {
          ans = mp[temp];
          res = temp;
        }
        temp = "";
        flag = false;
      }
    }
  }
  if(flag)
  {
    mp[temp]++;
    if(mp[temp]>ans)
    {
      ans = mp[temp];
      res = temp;
    }
  }
  cout<<res<<" "<<ans<<endl;
  return 0;
}