单词接龙 深搜

http://ayit.acmclub.com/index.php?app=problem_title&id=233&problem_id=21522

#include <iostream>
#include <string>
#include <limits.h>
#include <cstdio>
using namespace std;
string s[25];
char c;
int n,vis[25],m=0;
void dfs(string a,int sum)
{
    int i,j,k,t;
    for(i = 0; i < n; i++)
    {
        if(vis[i]<2)
        {
            int max = 0;
            for(j = 1; j<=s[i].size();j++)
            {
                if(a.size() <s[i].size())
                {
                    for(k = 0; k < a.size(); k++)
                    if(a[k] != s[i][k]) break;
                    if(k == a.size()) break;
                }
                for(k = a.size()-j,t= 0; t < j&&k<a.size(); t++,k++)
                {
                    if(a[k] != s[i][t]) break;
                }
                if(k == a.size()) {max = j;break;}
            }
            if(max == 0) continue;
            vis[i]++;
            dfs(s[i],sum+a.size() - max);
            vis[i]--;
        }
    }
    sum += a.size();
    if(sum>m) m= sum;
}
int main()
{
    int i;
    cin>>n;
    for(i = 0; i < n; i++)
    cin>>s[i];
    cin>>c;
    for(i = 0; i < n; i++)
    {
        if(s[i][0] == c)
        {
            vis[i]++;
            dfs(s[i],0);
            vis[i]--;
        }
    }
    cout<<m<<endl;
    return 0 ;
}