贪心，假如任意给出一个序列，如果两两交换了以后会变大，那么就交换，直到不能交换为止。

#include
     
      using namespace std;const int maxn = 51;string s[maxn];int rk[maxn];bool cmp(int x,int y){    int i = 0, j = 0, n1 = s[x].size(), n2 = s[y].size();    string *s1 = &s[x], *s2 = &s[y];    int ct = n1+n2;    while(ct--){        if(i == n1) i = 0,s1 = &s[y];        if(j == n2) j = 0,s2 = &s[x];        if(s1->at(i) != s2->at(j)) return s1->at(i) < s2->at(j);        i++;j++;    }    return false;}int main(){    //freopen("in.txt","r",stdin);    ios_base::sync_with_stdio(false);    int n;    while(cin>>n&&n){        for(int i = 0; i < n; i++) cin>>s[i], rk[i] = i;        sort(rk,rk+n,cmp);        for(int i = n-1; i>=0; i--) printf("%s",s[rk[i]].c_str());        puts("");    }    return 0;}