UVA 487 - Boggle Blitz

#include <iostream>
#include <algorithm>
#include <memory.h>
#include <cstdio>
#include <vector>
#include <string>
using namespace std;
const int MAX=21;

char table[MAX][MAX];
int n;
int di[]={-1,1,0,0,-1,-1,1,1};
int dj[]={0,0,-1,1,-1,1,-1,1};
vector<string>ans;
bool cmp(const string &cs1,const string &cs2){
if(cs1.size()<cs2.size())return true;
else if(cs1.size()==cs2.size()&&cs1<cs2)return true;
return false;
}
string stak;
void backtracking(int curi,int curj){
if(stak.size()>=3){
ans.push_back(stak);
}
for (int i=0;i<8;++i)
{
int ni=curi+di[i],nj=curj+dj[i];
if(ni>=0&&ni<n&&nj>=0&&nj<n&&table[ni][nj]>table[curi][curj]){
stak.push_back(table[ni][nj]);
backtracking(ni,nj);
stak.erase(stak.end()-1);
}
}
}
int main(){
int t;
scanf("%d",&t);
while (t--)
{
scanf("%d\n",&n);
ans.clear();
for (int i=0;i<n;++i)gets(table[i]);
for (int i=0;i<n;i++)
{
for (int j=0;j<n;++j)
{
stak.push_back(table[i][j]);
backtracking(i,j);
stak.erase(stak.end()-1);
}
}
sort(ans.begin(),ans.end(),cmp);
ans.erase(unique(ans.begin(),ans.end()),ans.end());
for (int i=0;i<ans.size();++i)printf("%s\n",ans[i].c_str());
if(t)printf("\n");
}
return 0;
}