#include <iostream>
#include <string>
#include <vector>
using namespace std;
int DFS(string begin,string target,vector<string> wards){
if(begin==target)
return 0;
int n=begin.size();
for(int i=0;i<n;i++){
if(begin[i]==target[i])
continue ;
string a=begin;
a[i]=target[i];
for(int j=0;j<wards.size();j++){
if(a==wards[j]){
return 1+DFS(a,target,wards);
}
}
}
}
int solution(string begin, string target, vector<string> words) {
int answer = 0;
return DFS(begin,target,words);
}
https://school.programmers.co.kr/learn/courses/30/lessons/43163