两个语句 不明白 return c1!=c2?c1<c2:c1<c2; cin.clear();

  return c1!=c2?c1<c2:c1<c2;
  cin.clear();
//这两个什么意思

#include <iostream>
#include<string>
#include<vector>
#include<algorithm>
using namespace std;

bool comp(const string &s1,const string &s2)
{
    int i,j,k,m,n;
    int c1=0,c2=0;
    for(i=0;i<s1.size();i++)
    {
        for(j=i+1;j<s1.size();j++)
        {
            if(s1[i]>s1[j])
            c1++;
        }
    }
    for(i=0;i<s2.size();i++)
    {
        for(j=i+1;j<s2.size();j++)
        {
            if(s2[i]>s2[j])
              c2++;
        }
    }
    return c1!=c2?c1<c2:c1<c2;
}
int main()
{
    string s;
    vector<string> v;
    int n,a,b;
    cin>>n;
    int i,j,k;
    int p=0;
    for(i=0;i<n;i++)
    {
        cin.clear();
        cin>>a>>b;
        v.clear();
        p++;
        for(j=0;j<b;j++)
        {
            cin>>s;
            v.push_back(s);
        }
        sort(v.begin(),v.end(),comp);
        if(p!=1)  cout<<endl;
        for(k=0;k<v.size();k++)
        {
            cout<<v[k]<<endl;
        }
    }
    return 0;
}