> 参照例程写的，例程是用cstdlib里的qsort
> 我用sort一遇到大数据,例如第3个数据n=99就RE了，本地也一样
> 
> #include<iostream>
> #include<vector>
> #include<cstring>
> #include<queue>
> #include<stack>
> #include<map>
> #include<set>
> #include<algorithm>
> #include<numeric>
> #include<cstdio>
> #include<cmath>
> #include<cctype>
> using namespace std;
> #define FOR(i,n) for (int i=0;i<n;i++)
> #define FORI(i,s) for (int i=0;i<s.size();i++)
> #define BEND(x) (x).begin(),(x).end()
> #define FORALL(it,st) for(typeof(st.begin())it=st.begin();it!=st.end();it++)
> const int MAXN=1024;
> char a[MAXN*MAXN];
> int p[MAXN*MAXN];
> int c[MAXN];
> char *prev;
> bool Cmp(int x,int y)
> {
>     return strcmp(a+x,a+y)<=0;
> }
> int common(int x,int y)
> {
>     int i;
>     for(i=0;i<MAXN;i++)
>         if(a[x+i]!=a[y+i]||!a[x+i]||!a[y+i])
>             return i;
> }
> int main()
> {
>     int n,i,j,k,s,best,l,r,done=0;
>     while(scanf("%d",&n)&&n)
>     {
>         if(done++)
>             printf("\n");
>         k=0;
>         for(i=s=0;i<n;i++,s+=MAXN)
>         {
>             scanf("%s",a+s);
>             for(j=s;a[j];j++)
>                 p[k++]=j;
>         }
>         stable_sort(p,p+k,Cmp);      ///就是这里导致RE的，换成sort的话
>         l=r=best=s=0;
>         memset(c,0,sizeof(c));
>         while(r<k)
>         {
>             while(s<=n/2&&r<k)
>                 if(!c[p[r++]/MAXN]++)
>                     s++;
>             while(s>n/2&&l<r)
>                 if(!--c[p[l++]/MAXN])
>                     s--;
>             if(l)
>                 best>?=common(p[l-1],p[r-1]);
>         }
>         if(best==0)
>         {
>             printf("?\n");
>             continue;
>         }
>         l=r=s=0;
>         memset(c,0,sizeof(c));
>         prev="";
>         while(r<k)
>         {
>             while(s<=n/2&&r<k)
>                 if(!c[p[r++]/MAXN]++)
>                     s++;
>             while(s>n/2&&l<r)
>                 if(!--c[p[l++]/MAXN])
>                     s--;
>             if(common(p[l-1],p[r-1])==best)
>                 if(strncmp(prev,a+p[l-1],best))
>                 {
>                     prev=a+p[l-1];
>                     for(j=0;j<best;j++)
>                         printf("%c",*(prev+j));
>                     printf("\n");
>                 }                    
>         }
>     }            
>     return 0;
> }

cmp函数里的<=应改为<